diff --git a/lib/blockchain/chain.js b/lib/blockchain/chain.js
index c7fb7fd2..87f55c5e 100644
--- a/lib/blockchain/chain.js
+++ b/lib/blockchain/chain.js
@@ -33,12 +33,11 @@ var VerifyResult = errors.VerifyResult;
  * @param {String?} options.name - Database name.
  * @param {String?} options.location - Database file location.
  * @param {String?} options.db - Database backend (`"leveldb"` by default).
- * @param {Number?} options.orphanLimit
+ * @param {Number?} options.maxOrphans
  * @param {Boolean?} options.spv
  * @property {Boolean} loaded
  * @property {ChainDB} db - Note that Chain `options` will be passed
  * to the instantiated ChainDB.
- * @property {Number} total
  * @property {Lock} locker
  * @property {Object} invalid
  * @property {ChainEntry?} tip
@@ -80,13 +79,10 @@ function Chain(options) {
   this.tip = null;
   this.height = -1;
   this.synced = false;
-  this.total = 0;
-  this.startTime = util.hrtime();
 
   this.orphanMap = {};
   this.orphanPrev = {};
   this.orphanCount = 0;
-  this.orphanSize = 0;
 
   this.db = new ChainDB(this);
 }
@@ -224,6 +220,7 @@ Chain.prototype.isGenesis = function isGenesis(block) {
  */
 
 Chain.prototype.verify = co(function* verify(block, prev, flags) {
+  var hash = block.hash('hex');
   var ret = new VerifyResult();
   var now = this.network.now();
   var height = prev.height + 1;
@@ -236,6 +233,14 @@ Chain.prototype.verify = co(function* verify(block, prev, flags) {
   if (block.prevBlock !== prev.hash)
     throw new VerifyError(block, 'invalid', 'bad-prevblk', 0);
 
+  // Verify a checkpoint if there is one.
+  if (!this.verifyCheckpoint(prev, hash)) {
+    throw new VerifyError(block,
+      'checkpoint',
+      'checkpoint mismatch',
+      100);
+  }
+
   // Skip everything when using checkpoints.
   // We can do this safely because every
   // block in between each checkpoint was
@@ -842,6 +847,7 @@ Chain.prototype.disconnect = co(function* disconnect(entry) {
   this.height = prev.height;
 
   this.emit('tip', prev);
+
   yield this.fire('disconnect', entry, block, view);
 });
 
@@ -891,6 +897,7 @@ Chain.prototype.reconnect = co(function* reconnect(entry) {
 
   this.emit('tip', entry);
   this.emit('reconnect', entry, block);
+
   yield this.fire('connect', entry, block, result.view);
 });
 
@@ -958,6 +965,7 @@ Chain.prototype.setBestChain = co(function* setBestChain(entry, block, prev, fla
 
   this.emit('tip', entry);
   this.emit('block', block, entry);
+
   yield this.fire('connect', entry, block, result.view);
 });
 
@@ -1173,15 +1181,16 @@ Chain.prototype.scan = co(function* scan(start, filter, iter) {
  * Add a block to the chain, perform all necessary verification.
  * @method
  * @param {Block} block
- * @param {Number} flags
+ * @param {Number?} flags
+ * @param {Number?} id
  * @returns {Promise}
  */
 
-Chain.prototype.add = co(function* add(block, flags) {
+Chain.prototype.add = co(function* add(block, flags, id) {
   var hash = block.hash('hex');
   var unlock = yield this.locker.lock(hash);
   try {
-    return yield this._add(block, flags);
+    return yield this._add(block, flags, id);
   } finally {
     unlock();
   }
@@ -1192,146 +1201,181 @@ Chain.prototype.add = co(function* add(block, flags) {
  * @method
  * @private
  * @param {Block} block
- * @param {Number} flags
+ * @param {Number?} flags
+ * @param {Number?} id
  * @returns {Promise}
  */
 
-Chain.prototype._add = co(function* add(block, flags) {
-  var initial = true;
-  var result = null;
-  var hash, entry, prev;
+Chain.prototype._add = co(function* add(block, flags, id) {
+  var hash = block.hash('hex');
+  var entry, prev;
 
   if (flags == null)
     flags = common.flags.DEFAULT_FLAGS;
 
-  assert(block);
+  if (id == null)
+    id = -1;
 
-  while (block) {
-    hash = block.hash('hex');
-
-    // Mark the start time.
-    this.mark();
-
-    // Special case for genesis block.
-    if (hash === this.network.genesis.hash) {
-      this.logger.debug('Saw genesis block: %s.', block.rhash());
-      throw new VerifyError(block, 'duplicate', 'duplicate', 0);
-    }
-
-    // Do we already have this block in the queue?
-    if (this.hasPending(hash)) {
-      this.logger.debug('Already have pending block: %s.', block.rhash());
-      throw new VerifyError(block, 'duplicate', 'duplicate', 0);
-    }
-
-    // If the block is already known to be
-    // an orphan, ignore it.
-    if (this.hasOrphan(hash)) {
-      this.logger.debug('Already have orphan block: %s.', block.rhash());
-      throw new VerifyError(block, 'duplicate', 'duplicate', 0);
-    }
-
-    // Do not revalidate known invalid blocks.
-    if (this.hasInvalid(hash, block)) {
-      this.logger.debug('Invalid ancestors for block: %s.', block.rhash());
-      throw new VerifyError(block, 'duplicate', 'duplicate', 100);
-    }
-
-    // Check the POW before doing anything.
-    if (flags & common.flags.VERIFY_POW) {
-      if (!block.verifyPOW())
-        throw new VerifyError(block, 'invalid', 'high-hash', 50);
-    }
-
-    // Do we already have this block?
-    if (yield this.db.hasEntry(hash)) {
-      this.logger.debug('Already have block: %s.', block.rhash());
-      throw new VerifyError(block, 'duplicate', 'duplicate', 0);
-    }
-
-    // Find the previous block entry.
-    prev = yield this.db.getEntry(block.prevBlock);
-
-    // If previous block wasn't ever seen,
-    // add it current to orphans and break.
-    if (!prev) {
-      assert(initial);
-      assert(!result);
-      this.storeOrphan(block);
-      break;
-    }
-
-    // Verify a checkpoint if there is one.
-    if (!this.verifyCheckpoint(prev, hash)) {
-      throw new VerifyError(block,
-        'checkpoint',
-        'checkpoint mismatch',
-        100);
-    }
-
-    // Explanation: we try to keep as much data
-    // off the javascript heap as possible. Blocks
-    // in the future may be 8mb or 20mb, who knows.
-    // In fullnode-mode we store the blocks in
-    // "compact" form (the headers plus the raw
-    // Buffer object) until they're ready to be
-    // fully validated here. They are deserialized,
-    // validated, and emitted. Hopefully the deserialized
-    // blocks get cleaned up by the GC quickly.
-    if (block.memory) {
-      try {
-        block = block.toBlock();
-      } catch (e) {
-        this.logger.error(e);
-        throw new VerifyError(block,
-          'malformed',
-          'error parsing message',
-          10);
-      }
-    }
-
-    // Create a new chain entry.
-    entry = ChainEntry.fromBlock(this, block, prev);
-
-    // The block is on a alternate chain if the
-    // chainwork is less than or equal to
-    // our tip's. Add the block but do _not_
-    // connect the inputs.
-    if (entry.chainwork.cmp(this.tip.chainwork) <= 0) {
-      // Save block to an alternate chain.
-      yield this.saveAlternate(entry, block, prev, flags);
-    } else {
-      // Attempt to add block to the chain index.
-      yield this.setBestChain(entry, block, prev, flags);
-    }
-
-    // Emit the resolved orphan.
-    if (!initial) {
-      this.logger.debug(
-        'Orphan block was resolved: %s (%d).',
-        block.rhash(), entry.height);
-      this.emit('resolved', block, entry);
-    }
-
-    // Keep track of stats.
-    this.finish(block, entry);
-
-    // Try to resolve orphan chain.
-    block = this.resolveOrphan(hash);
-    initial = false;
-
-    if (!result)
-      result = entry;
+  // Special case for genesis block.
+  if (hash === this.network.genesis.hash) {
+    this.logger.debug('Saw genesis block: %s.', block.rhash());
+    throw new VerifyError(block, 'duplicate', 'duplicate', 0);
   }
 
-  // Failsafe for large orphan chains. Do not
-  // allow more than 20mb stored in memory.
-  this.pruneOrphans();
+  // Do we already have this block in the queue?
+  if (this.hasPending(hash)) {
+    this.logger.debug('Already have pending block: %s.', block.rhash());
+    throw new VerifyError(block, 'duplicate', 'duplicate', 0);
+  }
+
+  // If the block is already known to be
+  // an orphan, ignore it.
+  if (this.hasOrphan(hash)) {
+    this.logger.debug('Already have orphan block: %s.', block.rhash());
+    throw new VerifyError(block, 'duplicate', 'duplicate', 0);
+  }
+
+  // Do not revalidate known invalid blocks.
+  if (this.hasInvalid(hash, block)) {
+    this.logger.debug('Invalid ancestors for block: %s.', block.rhash());
+    throw new VerifyError(block, 'duplicate', 'duplicate', 100);
+  }
+
+  // Check the POW before doing anything.
+  if (flags & common.flags.VERIFY_POW) {
+    if (!block.verifyPOW())
+      throw new VerifyError(block, 'invalid', 'high-hash', 50);
+  }
+
+  // Do we already have this block?
+  if (yield this.db.hasEntry(hash)) {
+    this.logger.debug('Already have block: %s.', block.rhash());
+    throw new VerifyError(block, 'duplicate', 'duplicate', 0);
+  }
+
+  // Find the previous block entry.
+  prev = yield this.db.getEntry(block.prevBlock);
+
+  // If previous block wasn't ever seen,
+  // add it current to orphans and return.
+  if (!prev) {
+    this.storeOrphan(block, flags, id);
+    return null;
+  }
+
+  // Connect the block.
+  entry = yield this.connect(prev, block, flags);
+
+  // Handle any orphans.
+  if (this.hasNextOrphan(hash))
+    yield this.handleOrphans(entry);
+
+  return entry;
+});
+
+/**
+ * Connect block to chain.
+ * @method
+ * @private
+ * @param {ChainEntry} prev
+ * @param {Block} block
+ * @param {Number} flags
+ * @returns {Promise}
+ */
+
+Chain.prototype.connect = co(function* connect(prev, block, flags) {
+  var start = util.hrtime();
+  var entry;
+
+  // Sanity check.
+  assert(block.prevBlock === prev.hash);
+
+  // Explanation: we try to keep as much data
+  // off the javascript heap as possible. Blocks
+  // in the future may be 8mb or 20mb, who knows.
+  // In fullnode-mode we store the blocks in
+  // "compact" form (the headers plus the raw
+  // Buffer object) until they're ready to be
+  // fully validated here. They are deserialized,
+  // validated, and connected. Hopefully the
+  // deserialized blocks get cleaned up by the
+  // GC quickly.
+  if (block.memory) {
+    try {
+      block = block.toBlock();
+    } catch (e) {
+      this.logger.error(e);
+      throw new VerifyError(block,
+        'malformed',
+        'error parsing message',
+        10);
+    }
+  }
+
+  // Create a new chain entry.
+  entry = ChainEntry.fromBlock(this, block, prev);
+
+  // The block is on a alternate chain if the
+  // chainwork is less than or equal to
+  // our tip's. Add the block but do _not_
+  // connect the inputs.
+  if (entry.chainwork.cmp(this.tip.chainwork) <= 0) {
+    // Save block to an alternate chain.
+    yield this.saveAlternate(entry, block, prev, flags);
+  } else {
+    // Attempt to add block to the chain index.
+    yield this.setBestChain(entry, block, prev, flags);
+  }
+
+  // Keep track of stats.
+  this.logStatus(start, block, entry);
 
   // Check sync state.
   this.maybeSync();
 
-  return result;
+  return entry;
+});
+
+/**
+ * Handle orphans.
+ * @method
+ * @private
+ * @param {ChainEntry} entry
+ * @returns {Promise}
+ */
+
+Chain.prototype.handleOrphans = co(function* handleOrphans(entry) {
+  var orphan = this.resolveOrphan(entry.hash);
+  var block, flags, id;
+
+  while (orphan) {
+    block = orphan.block;
+    flags = orphan.flags;
+    id = orphan.id;
+
+    try {
+      entry = yield this.connect(entry, block, flags);
+    } catch (err) {
+      if (err.type === 'VerifyError') {
+        this.logger.warning(
+          'Could not resolve orphan block %s: %s.',
+          block.rhash(), err.message);
+
+        this.emit('bad orphan', err, id);
+
+        break;
+      }
+      throw err;
+    }
+
+    this.logger.debug(
+      'Orphan block was resolved: %s (%d).',
+      block.rhash(), entry.height);
+
+    this.emit('resolved', block, entry);
+
+    orphan = this.resolveOrphan(entry.hash);
+  }
 });
 
 /**
@@ -1344,43 +1388,37 @@ Chain.prototype.isSlow = function isSlow() {
   if (this.options.spv)
     return false;
 
-  if (this.total === 1 || this.total % 20 === 0)
+  if (this.synced)
     return true;
 
-  return this.synced || this.height >= this.network.block.slowHeight;
-};
+  if (this.height === 1 || this.height % 20 === 0)
+    return true;
 
-/**
- * Mark the start time for block processing.
- * @private
- */
+  if (this.height >= this.network.block.slowHeight)
+    return true;
 
-Chain.prototype.mark = function mark() {
-  this.startTime = util.hrtime();
+  return false;
 };
 
 /**
  * Calculate the time difference from
  * start time and log block.
  * @private
+ * @param {Array} start
  * @param {Block} block
  * @param {ChainEntry} entry
  */
 
-Chain.prototype.finish = function finish(block, entry) {
+Chain.prototype.logStatus = function logStatus(start, block, entry) {
   var elapsed;
 
-  // Keep track of total blocks handled.
-  this.total += 1;
-
   if (!this.isSlow())
     return;
 
   // Report memory for debugging.
-  util.gc();
   this.logger.memory();
 
-  elapsed = util.hrtime(this.startTime);
+  elapsed = util.hrtime(start);
 
   this.logger.info(
     'Block %s (%d) added to chain (size=%d txs=%d time=%d).',
@@ -1443,29 +1481,32 @@ Chain.prototype.verifyCheckpoint = function verifyCheckpoint(prev, hash) {
  * Store an orphan.
  * @private
  * @param {Block} block
+ * @param {Number?} flags
+ * @param {Number?} id
  */
 
-Chain.prototype.storeOrphan = function storeOrphan(block) {
+Chain.prototype.storeOrphan = function storeOrphan(block, flags, id) {
   var hash = block.hash('hex');
   var height = block.getCoinbaseHeight();
   var orphan = this.orphanPrev[block.prevBlock];
 
   // The orphan chain forked.
   if (orphan) {
-    assert(orphan.hash('hex') !== hash);
-    assert(orphan.prevBlock === block.prevBlock);
+    assert(orphan.block.hash('hex') !== hash);
+    assert(orphan.block.prevBlock === block.prevBlock);
 
     this.logger.warning(
       'Removing forked orphan block: %s (%d).',
-      orphan.rhash(), height);
+      orphan.block.rhash(), height);
 
-    this.resolveOrphan(block.prevBlock);
+    this.removeOrphan(orphan.block.hash('hex'));
   }
 
-  this.orphanCount++;
-  this.orphanSize += block.getSize();
-  this.orphanPrev[block.prevBlock] = block;
-  this.orphanMap[hash] = block;
+  this.limitOrphans();
+
+  orphan = new Orphan(block, flags, id);
+
+  this.addOrphan(orphan);
 
   this.logger.debug(
     'Storing orphan block: %s (%d).',
@@ -1474,26 +1515,75 @@ Chain.prototype.storeOrphan = function storeOrphan(block) {
   this.emit('orphan', block);
 };
 
+/**
+ * Add an orphan.
+ * @private
+ * @param {Orphan} orphan
+ * @returns {Orphan}
+ */
+
+Chain.prototype.addOrphan = function addOrphan(orphan) {
+  var block = orphan.block;
+  var hash = block.hash('hex');
+
+  assert(!this.orphanMap[hash]);
+  assert(!this.orphanPrev[block.prevBlock]);
+  assert(this.orphanCount >= 0);
+
+  this.orphanMap[hash] = orphan;
+  this.orphanPrev[block.prevBlock] = orphan;
+  this.orphanCount += 1;
+
+  return orphan;
+};
+
+/**
+ * Remove an orphan.
+ * @private
+ * @param {Hash} hash
+ * @returns {Orphan}
+ */
+
+Chain.prototype.removeOrphan = function removeOrphan(hash) {
+  var orphan = this.orphanMap[hash];
+  var block = orphan.block;
+
+  assert(this.orphanMap[hash]);
+  assert(this.orphanPrev[block.prevBlock]);
+  assert(this.orphanCount > 0);
+
+  delete this.orphanMap[hash];
+  delete this.orphanPrev[block.prevBlock];
+  this.orphanCount -= 1;
+
+  return orphan;
+};
+
+/**
+ * Test whether a hash would resolve the next orphan.
+ * @private
+ * @param {Hash} hash - Previous block hash.
+ * @returns {Boolean}
+ */
+
+Chain.prototype.hasNextOrphan = function hasNextOrphan(hash) {
+  return this.orphanPrev[hash] != null;
+};
+
 /**
  * Resolve an orphan.
  * @private
  * @param {Hash} hash - Previous block hash.
- * @returns {Block}
+ * @returns {Orphan}
  */
 
 Chain.prototype.resolveOrphan = function resolveOrphan(hash) {
-  var block = this.orphanPrev[hash];
+  var orphan = this.orphanPrev[hash];
 
-  if (!block)
+  if (!orphan)
     return;
 
-  delete this.orphanMap[block.hash('hex')];
-  delete this.orphanPrev[hash];
-
-  this.orphanCount--;
-  this.orphanSize -= block.getSize();
-
-  return block;
+  return this.removeOrphan(orphan.block.hash('hex'));
 };
 
 /**
@@ -1502,18 +1592,15 @@ Chain.prototype.resolveOrphan = function resolveOrphan(hash) {
 
 Chain.prototype.purgeOrphans = function purgeOrphans() {
   var count = this.orphanCount;
-  var size = this.orphanSize;
 
   if (count === 0)
     return;
 
-  this.orphanPrev = {};
   this.orphanMap = {};
+  this.orphanPrev = {};
   this.orphanCount = 0;
-  this.orphanSize = 0;
 
-  this.logger.debug('Purged %d orphans (%dmb).',
-    count, util.mb(size));
+  this.logger.debug('Purged %d orphans.', count);
 };
 
 /**
@@ -1521,59 +1608,38 @@ Chain.prototype.purgeOrphans = function purgeOrphans() {
  * coinbase height (likely to be the peer's tip).
  */
 
-Chain.prototype.pruneOrphans = function pruneOrphans() {
-  var i, hashes, hash, orphan, height;
-  var bestOrphan, bestHeight, lastOrphan;
-
-  if (this.orphanSize <= this.options.orphanLimit)
-    return false;
-
-  this.logger.warning('Pruning %d (%dmb) orphans!',
-    this.orphanCount, util.mb(this.orphanSize));
-
-  hashes = Object.keys(this.orphanPrev);
-
-  if (hashes.length === 0)
-    return false;
-
-  for (i = 0; i < hashes.length; i++) {
-    hash = hashes[i];
-    orphan = this.orphanPrev[hash];
-    height = orphan.getCoinbaseHeight();
-
-    delete this.orphanPrev[hash];
-
-    if (!bestOrphan || height > bestHeight) {
-      bestOrphan = orphan;
-      bestHeight = height;
-    }
-
-    lastOrphan = orphan;
-  }
-
-  // Save the best for last... or the
-  // last for best in this case.
-  if (bestHeight === -1)
-    bestOrphan = lastOrphan;
-
-  hashes = Object.keys(this.orphanMap);
+Chain.prototype.limitOrphans = function limitOrphans() {
+  var now = util.now();
+  var hashes = Object.keys(this.orphanMap);
+  var total = 0;
+  var i, hash, orphan, oldest;
 
   for (i = 0; i < hashes.length; i++) {
     hash = hashes[i];
     orphan = this.orphanMap[hash];
 
-    delete this.orphanMap[hash];
+    if (now < orphan.ts + 60 * 60) {
+      if (!oldest || orphan.ts < oldest.ts)
+        oldest = orphan;
+      continue;
+    }
 
-    if (orphan !== bestOrphan)
-      this.emit('unresolved', orphan);
+    this.removeOrphan(hash);
+
+    total++;
   }
 
-  this.orphanPrev[bestOrphan.prevBlock] = bestOrphan;
-  this.orphanMap[bestOrphan.hash('hex')] = bestOrphan;
-  this.orphanCount = 1;
-  this.orphanSize = bestOrphan.getSize();
+  if (this.orphanCount >= this.options.maxOrphans) {
+    if (total === 0 && oldest) {
+      hash = oldest.block.hash('hex');
+      this.removeOrphan(hash);
+    }
+  }
 
-  return true;
+  if (total > 0)
+    this.logger.warning('Pruned %d orphans!', total);
+
+  return total;
 };
 
 /**
@@ -1850,13 +1916,18 @@ Chain.prototype._getLocator = co(function* getLocator(start) {
  */
 
 Chain.prototype.getOrphanRoot = function getOrphanRoot(hash) {
-  var root;
+  var root, orphan;
 
   assert(hash);
 
-  while (this.orphanMap[hash]) {
+  for (;;) {
+    orphan = this.orphanMap[hash];
+
+    if (!orphan)
+      break;
+
     root = hash;
-    hash = this.orphanMap[hash].prevBlock;
+    hash = orphan.block.prevBlock;
   }
 
   return root;
@@ -2330,7 +2401,7 @@ function ChainOptions(options) {
 
   this.coinCache = 0;
   this.entryCache = 5000;
-  this.orphanLimit = 20 << 20;
+  this.maxOrphans = 20;
   this.checkpoints = true;
 
   if (options)
@@ -2428,9 +2499,9 @@ ChainOptions.prototype.fromOptions = function fromOptions(options) {
     this.entryCache = options.entryCache;
   }
 
-  if (options.orphanLimit != null) {
-    assert(util.isNumber(options.orphanLimit));
-    this.orphanLimit = options.orphanLimit;
+  if (options.maxOrphans != null) {
+    assert(util.isNumber(options.maxOrphans));
+    this.maxOrphans = options.maxOrphans;
   }
 
   if (options.checkpoints != null) {
@@ -2555,6 +2626,19 @@ function ContextResult(view, state) {
   this.state = state;
 }
 
+/**
+ * Orphan
+ * @constructor
+ * @ignore
+ */
+
+function Orphan(block, flags, id) {
+  this.block = block;
+  this.flags = flags;
+  this.id = id;
+  this.ts = util.now();
+}
+
 /*
  * Expose
  */
diff --git a/lib/mempool/mempool.js b/lib/mempool/mempool.js
index 5efbc139..e61cdbd2 100644
--- a/lib/mempool/mempool.js
+++ b/lib/mempool/mempool.js
@@ -292,7 +292,7 @@ Mempool.prototype._removeBlock = co(function* removeBlock(block, txs) {
       continue;
 
     try {
-      yield this.insertTX(tx);
+      yield this.insertTX(tx, -1);
       total++;
     } catch (e) {
       this.emit('error', e);
@@ -448,25 +448,6 @@ Mempool.prototype.limitSize = function limitSize(added) {
   return !this.hasEntry(added);
 };
 
-/**
- * Purge orphan transactions from the mempool.
- */
-
-Mempool.prototype.limitOrphans = function limitOrphans() {
-  var orphans = Object.keys(this.orphans);
-  var i, hash;
-
-  while (this.totalOrphans > this.options.maxOrphans) {
-    i = crypto.randomRange(0, orphans.length);
-    hash = orphans[i];
-    orphans.splice(i, 1);
-
-    this.logger.spam('Removing orphan %s from mempool.', util.revHex(hash));
-
-    this.removeOrphan(hash);
-  }
-};
-
 /**
  * Retrieve a transaction from the mempool.
  * @param {Hash} hash
@@ -721,14 +702,15 @@ Mempool.prototype.hasReject = function hasReject(hash) {
  * fully processed.
  * @method
  * @param {TX} tx
+ * @param {Number?} id
  * @returns {Promise}
  */
 
-Mempool.prototype.addTX = co(function* addTX(tx) {
+Mempool.prototype.addTX = co(function* addTX(tx, id) {
   var hash = tx.hash('hex');
   var unlock = yield this.locker.lock(hash);
   try {
-    return yield this._addTX(tx);
+    return yield this._addTX(tx, id);
   } finally {
     unlock();
   }
@@ -739,14 +721,18 @@ Mempool.prototype.addTX = co(function* addTX(tx) {
  * @method
  * @private
  * @param {TX} tx
+ * @param {Number?} id
  * @returns {Promise}
  */
 
-Mempool.prototype._addTX = co(function* _addTX(tx) {
+Mempool.prototype._addTX = co(function* _addTX(tx, id) {
   var missing;
 
+  if (id == null)
+    id = -1;
+
   try {
-    missing = yield this.insertTX(tx);
+    missing = yield this.insertTX(tx, id);
   } catch (err) {
     if (err.type === 'VerifyError') {
       if (!tx.hasWitness() && !err.malleated)
@@ -768,11 +754,13 @@ Mempool.prototype._addTX = co(function* _addTX(tx) {
  * @method
  * @private
  * @param {TX} tx
+ * @param {Number?} id
  * @returns {Promise}
  */
 
-Mempool.prototype.insertTX = co(function* insertTX(tx) {
+Mempool.prototype.insertTX = co(function* insertTX(tx, id) {
   var lockFlags = common.lockFlags.STANDARD_LOCKTIME_FLAGS;
+  var height = this.chain.height;
   var hash = tx.hash('hex');
   var ret = new VerifyResult();
   var entry, view, missing;
@@ -883,11 +871,11 @@ Mempool.prototype.insertTX = co(function* insertTX(tx) {
 
   // Maybe store as an orphan.
   if (missing)
-    return this.storeOrphan(tx, missing);
+    return this.storeOrphan(tx, missing, id);
 
   // Create a new mempool entry
   // at current chain height.
-  entry = MempoolEntry.fromTX(tx, view, this.chain.height);
+  entry = MempoolEntry.fromTX(tx, view, height);
 
   // Contextual verification.
   yield this.verify(entry, view);
@@ -902,6 +890,8 @@ Mempool.prototype.insertTX = co(function* insertTX(tx) {
       'mempool full',
       0);
   }
+
+  return null;
 });
 
 /**
@@ -1498,9 +1488,11 @@ Mempool.prototype.hasOrphan = function hasOrphan(hash) {
 /**
  * Store an orphaned transaction.
  * @param {TX} tx
+ * @param {Hash[]} missing
+ * @param {Number} id
  */
 
-Mempool.prototype.storeOrphan = function storeOrphan(tx, missing) {
+Mempool.prototype.storeOrphan = function storeOrphan(tx, missing, id) {
   var hash = tx.hash('hex');
   var i, prev;
 
@@ -1520,60 +1512,73 @@ Mempool.prototype.storeOrphan = function storeOrphan(tx, missing) {
     }
   }
 
+  if (this.options.maxOrphans === 0)
+    return [];
+
+  this.limitOrphans();
+
   for (i = 0; i < missing.length; i++) {
     prev = missing[i];
 
     if (!this.waiting[prev])
-      this.waiting[prev] = [];
+      this.waiting[prev] = new Map();
 
-    this.waiting[prev].push(hash);
+    this.waiting[prev].insert(hash);
   }
 
-  this.orphans[hash] = new Orphan(tx, missing.length);
+  this.orphans[hash] = new Orphan(tx, missing.length, id);
   this.totalOrphans++;
 
   this.logger.debug('Added orphan %s to mempool.', tx.txid());
 
   this.emit('add orphan', tx);
 
-  this.limitOrphans();
-
   return missing;
 };
 
 /**
  * Resolve orphans and attempt to add to mempool.
  * @method
- * @param {TX} tx
+ * @param {TX} parent
  * @returns {Promise} - Returns {@link TX}[].
  */
 
-Mempool.prototype.handleOrphans = co(function* handleOrphans(tx) {
-  var resolved = this.resolveOrphans(tx);
-  var i, orphan;
+Mempool.prototype.handleOrphans = co(function* handleOrphans(parent) {
+  var resolved = this.resolveOrphans(parent);
+  var i, orphan, tx, missing;
 
   for (i = 0; i < resolved.length; i++) {
     orphan = resolved[i];
 
     try {
-      yield this.insertTX(orphan);
+      tx = orphan.toTX();
+    } catch (e) {
+      this.logger.warning('%s %s',
+        'Warning: possible memory corruption.',
+        'Orphan failed deserialization.');
+    }
+
+    try {
+      missing = yield this.insertTX(tx, -1);
     } catch (err) {
       if (err.type === 'VerifyError') {
         this.logger.debug(
           'Could not resolve orphan %s: %s.',
-          orphan.txid(), err.message);
+          tx.txid(), err.message);
 
-        if (!orphan.hasWitness() && !err.malleated)
-          this.rejects.add(orphan.hash());
+        if (!tx.hasWitness() && !err.malleated)
+          this.rejects.add(tx.hash());
+
+        this.emit('bad orphan', err, orphan.id);
 
         continue;
       }
       throw err;
     }
 
-    this.logger.debug(
-      'Resolved orphan %s in mempool (txs=%d).',
-      orphan.txid(), this.totalTX);
+    assert(!missing);
+
+    this.logger.debug('Resolved orphan %s in mempool.', tx.txid());
   }
 
   return resolved;
@@ -1583,37 +1588,33 @@ Mempool.prototype.handleOrphans = co(function* handleOrphans(tx) {
  * Potentially resolve any transactions
  * that redeem the passed-in transaction.
  * Deletes all orphan entries and
- * returns orphan hashes.
- * @param {TX} tx
- * @returns {TX[]} Resolved
+ * returns orphan objects.
+ * @param {TX} parent
+ * @returns {Orphan[]}
  */
 
-Mempool.prototype.resolveOrphans = function resolveOrphans(tx) {
-  var hash = tx.hash('hex');
+Mempool.prototype.resolveOrphans = function resolveOrphans(parent) {
+  var hash = parent.hash('hex');
+  var map = this.waiting[hash];
   var resolved = [];
-  var hashes = this.waiting[hash];
-  var i, orphanHash, orphan;
+  var i, hashes, orphanHash, orphan;
 
-  if (!hashes)
+  if (!map)
     return resolved;
 
+  hashes = map.keys();
+  assert(hashes.length > 0);
+
   for (i = 0; i < hashes.length; i++) {
     orphanHash = hashes[i];
     orphan = this.getOrphan(orphanHash);
 
-    if (!orphan)
-      continue;
+    assert(orphan);
 
     if (--orphan.missing === 0) {
       delete this.orphans[orphanHash];
       this.totalOrphans--;
-      try {
-        resolved.push(orphan.toTX());
-      } catch (e) {
-        this.logger.warning('%s %s',
-          'Warning: possible memory corruption.',
-          'Orphan failed deserialization.');
-      }
+      resolved.push(orphan);
     }
   }
 
@@ -1625,14 +1626,15 @@ Mempool.prototype.resolveOrphans = function resolveOrphans(tx) {
 /**
  * Remove a transaction from the mempool.
  * @param {Hash} tx
+ * @returns {Boolean}
  */
 
 Mempool.prototype.removeOrphan = function removeOrphan(hash) {
   var orphan = this.getOrphan(hash);
-  var i, j, tx, hashes, prevout, prev;
+  var i, tx, map, prevout, prev;
 
   if (!orphan)
-    return;
+    return false;
 
   try {
     tx = orphan.toTX();
@@ -1649,19 +1651,16 @@ Mempool.prototype.removeOrphan = function removeOrphan(hash) {
 
   for (i = 0; i < prevout.length; i++) {
     prev = prevout[i];
-    hashes = this.waiting[prev];
+    map = this.waiting[prev];
 
-    if (!hashes)
+    if (!map)
       continue;
 
-    j = hashes.indexOf(hash);
+    assert(map.has(hash));
 
-    if (j === -1)
-      continue;
+    map.remove(hash);
 
-    hashes.splice(j, 1);
-
-    if (hashes.length === 0)
+    if (map.size === 0)
       delete this.waiting[prev];
   }
 
@@ -1669,6 +1668,30 @@ Mempool.prototype.removeOrphan = function removeOrphan(hash) {
   this.totalOrphans--;
 
   this.emit('remove orphan', tx);
+
+  return true;
+};
+
+/**
+ * Remove a random orphan transaction from the mempool.
+ * @returns {Boolean}
+ */
+
+Mempool.prototype.limitOrphans = function limitOrphans() {
+  var hashes = Object.keys(this.orphans);
+  var index, hash;
+
+  if (this.totalOrphans < this.options.maxOrphans)
+    return false;
+
+  index = crypto.randomRange(0, hashes.length);
+  hash = hashes[index];
+
+  this.logger.debug('Removing orphan %s from mempool.', util.revHex(hash));
+
+  this.removeOrphan(hash);
+
+  return true;
 };
 
 /**
@@ -2059,7 +2082,7 @@ MempoolOptions.prototype.fromOptions = function fromOptions(options) {
   }
 
   if (options.limitFreeRelay != null) {
-    assert(util.isNumber(options.limitFreeRelay));
+    assert(util.isUInt32(options.limitFreeRelay));
     this.limitFreeRelay = options.limitFreeRelay;
   }
 
@@ -2094,27 +2117,27 @@ MempoolOptions.prototype.fromOptions = function fromOptions(options) {
   }
 
   if (options.maxSize != null) {
-    assert(util.isNumber(options.maxSize));
+    assert(util.isUInt53(options.maxSize));
     this.maxSize = options.maxSize;
   }
 
   if (options.maxOrphans != null) {
-    assert(util.isNumber(options.maxOrphans));
+    assert(util.isUInt32(options.maxOrphans));
     this.maxOrphans = options.maxOrphans;
   }
 
   if (options.maxAncestors != null) {
-    assert(util.isNumber(options.maxAncestors));
+    assert(util.isUInt32(options.maxAncestors));
     this.maxAncestors = options.maxAncestors;
   }
 
   if (options.expiryTime != null) {
-    assert(util.isNumber(options.expiryTime));
+    assert(util.isUInt32(options.expiryTime));
     this.expiryTime = options.expiryTime;
   }
 
   if (options.minRelay != null) {
-    assert(util.isNumber(options.minRelay));
+    assert(util.isUint53(options.minRelay));
     this.minRelay = options.minRelay;
   }
 
@@ -2135,12 +2158,12 @@ MempoolOptions.prototype.fromOptions = function fromOptions(options) {
   }
 
   if (options.maxFiles != null) {
-    assert(util.isNumber(options.maxFiles));
+    assert(util.isUInt32(options.maxFiles));
     this.maxFiles = options.maxFiles;
   }
 
   if (options.cacheSize != null) {
-    assert(util.isNumber(options.cacheSize));
+    assert(util.isUInt53(options.cacheSize));
     this.cacheSize = options.cacheSize;
   }
 
@@ -2382,11 +2405,13 @@ IndexedCoin.prototype.toCoin = function toCoin() {
  * @ignore
  * @param {TX} tx
  * @param {Hash[]} missing
+ * @param {Number} id
  */
 
-function Orphan(tx, missing) {
+function Orphan(tx, missing, id) {
   this.raw = tx.toRaw();
   this.missing = missing;
+  this.id = id;
 }
 
 Orphan.prototype.toTX = function toTX() {
diff --git a/lib/net/packets.js b/lib/net/packets.js
index 709809ed..a3ad3f54 100644
--- a/lib/net/packets.js
+++ b/lib/net/packets.js
@@ -1674,10 +1674,11 @@ RejectPacket.fromRaw = function fromRaw(data, enc) {
  * @private
  * @param {Number} code
  * @param {String} reason
- * @param {(TX|Block)?} msg
+ * @param {String?} msg
+ * @param {Hash?} hash
  */
 
-RejectPacket.prototype.fromReason = function fromReason(code, reason, msg) {
+RejectPacket.prototype.fromReason = function fromReason(code, reason, msg, hash) {
   if (typeof code === 'string')
     code = RejectPacket.codes[code.toUpperCase()];
 
@@ -1692,8 +1693,9 @@ RejectPacket.prototype.fromReason = function fromReason(code, reason, msg) {
   this.reason = reason;
 
   if (msg) {
-    this.message = (msg instanceof TX) ? 'tx' : 'block';
-    this.hash = msg.hash('hex');
+    assert(hash);
+    this.message = msg;
+    this.hash = hash;
   }
 
   return this;
@@ -1703,12 +1705,13 @@ RejectPacket.prototype.fromReason = function fromReason(code, reason, msg) {
  * Instantiate reject packet from reason message.
  * @param {Number} code
  * @param {String} reason
- * @param {(TX|Block)?} obj
+ * @param {String?} msg
+ * @param {Hash?} hash
  * @returns {RejectPacket}
  */
 
-RejectPacket.fromReason = function fromReason(code, reason, obj) {
-  return new RejectPacket().fromReason(code, reason, obj);
+RejectPacket.fromReason = function fromReason(code, reason, msg, hash) {
+  return new RejectPacket().fromReason(code, reason, msg, hash);
 };
 
 /**
diff --git a/lib/net/peer.js b/lib/net/peer.js
index bfe64fe3..2c1018fa 100644
--- a/lib/net/peer.js
+++ b/lib/net/peer.js
@@ -79,7 +79,7 @@ function Peer(options) {
   this.parser = new Parser(this.network);
   this.framer = new Framer(this.network);
 
-  this.id = Peer.uid++;
+  this.id = -1;
   this.socket = null;
   this.opened = false;
   this.outbound = false;
@@ -149,13 +149,6 @@ function Peer(options) {
 
 util.inherits(Peer, EventEmitter);
 
-/**
- * Peer ID counter.
- * @type {Number}
- */
-
-Peer.uid = 0;
-
 /**
  * Max output bytes buffered before
  * invoking stall behavior for peer.
@@ -2151,12 +2144,12 @@ Peer.prototype.sendMempool = function sendMempool() {
  * @param {TX|Block} msg
  */
 
-Peer.prototype.sendReject = function sendReject(code, reason, msg) {
-  var reject = packets.RejectPacket.fromReason(code, reason, msg);
+Peer.prototype.sendReject = function sendReject(code, reason, msg, hash) {
+  var reject = packets.RejectPacket.fromReason(code, reason, msg, hash);
 
   if (msg) {
     this.logger.debug('Rejecting %s %s (%s): code=%s reason=%s.',
-      reject.message, msg.rhash(), this.hostname(), code, reason);
+      msg, util.revHex(hash), this.hostname(), code, reason);
   } else {
     this.logger.debug('Rejecting packet from %s: code=%s reason=%s.',
       this.hostname(), code, reason);
@@ -2223,16 +2216,14 @@ Peer.prototype.ban = function ban() {
 /**
  * Send a `reject` packet to peer.
  * @see Framer.reject
- * @param {(TX|Block)?} msg
- * @param {String} code
- * @param {String} reason
- * @param {Number} score
+ * @param {String msg
+ * @param {VerifyError} err
  * @returns {Boolean}
  */
 
-Peer.prototype.reject = function reject(msg, code, reason, score) {
-  this.sendReject(code, reason, msg);
-  return this.increaseBan(score);
+Peer.prototype.reject = function reject(msg, err) {
+  this.sendReject(err.code, err.reason, msg, err.hash);
+  return this.increaseBan(err.score);
 };
 
 /**
diff --git a/lib/net/pool.js b/lib/net/pool.js
index 46267295..83a8a314 100644
--- a/lib/net/pool.js
+++ b/lib/net/pool.js
@@ -109,6 +109,7 @@ function Pool(options) {
   this.peers = new PeerList();
   this.authdb = new BIP150.AuthDB(this.options);
   this.hosts = new HostList(this.options);
+  this.id = 0;
 
   if (this.options.spv)
     this.spvFilter = Bloom.fromRate(20000, 0.001, Bloom.flags.ALL);
@@ -190,6 +191,10 @@ Pool.prototype._init = function _init() {
       this.mempool.on('tx', function(tx) {
         self.announceTX(tx);
       });
+
+      this.mempool.on('bad orphan', function(err, id) {
+        self.handleBadOrphan('tx', err, id);
+      });
     }
 
     // Normally we would also broadcast
@@ -203,6 +208,10 @@ Pool.prototype._init = function _init() {
         return;
       self.announceBlock(block);
     });
+
+    this.chain.on('bad orphan', function(err, id) {
+      self.handleBadOrphan('block', err, id);
+    });
   }
 };
 
@@ -1162,6 +1171,29 @@ Pool.prototype.createInbound = function createInbound(socket) {
   return peer;
 };
 
+/**
+ * Allocate new peer id.
+ * @returns {Number}
+ */
+
+Pool.prototype.uid = function uid() {
+  var MAX = util.MAX_SAFE_INTEGER;
+
+  if (this.id >= MAX - this.peers.size() - 1)
+    this.id = 0;
+
+  // Once we overflow, there's a chance
+  // of collisions. Unlikely to happen
+  // unless we have tried to connect 9
+  // quadrillion times, but still
+  // account for it.
+  do {
+    this.id += 1;
+  } while (this.peers.find(this.id));
+
+  return this.id;
+};
+
 /**
  * Bind to peer events.
  * @private
@@ -1171,6 +1203,8 @@ Pool.prototype.createInbound = function createInbound(socket) {
 Pool.prototype.bindPeer = function bindPeer(peer) {
   var self = this;
 
+  peer.id = this.uid();
+
   peer.onPacket = function onPacket(packet) {
     return self.handlePacket(peer, packet);
   };
@@ -2265,10 +2299,10 @@ Pool.prototype._addBlock = co(function* addBlock(peer, block, flags) {
   peer.blockTime = util.ms();
 
   try {
-    entry = yield this.chain.add(block, flags);
+    entry = yield this.chain.add(block, flags, peer.id);
   } catch (err) {
     if (err.type === 'VerifyError') {
-      peer.reject(block, err.code, err.reason, err.score);
+      peer.reject('block', err);
       this.logger.warning(err);
       return;
     }
@@ -2395,6 +2429,33 @@ Pool.prototype.switchSync = co(function* switchSync(peer, hash) {
   yield this.getBlocks(peer, hash);
 });
 
+/**
+ * Handle bad orphan.
+ * @method
+ * @private
+ * @param {String} msg
+ * @param {VerifyError} err
+ * @param {Number} id
+ */
+
+Pool.prototype.handleBadOrphan = function handleBadOrphan(msg, err, id) {
+  var peer = this.peers.find(id);
+
+  if (!peer) {
+    this.logger.warning(
+      'Could not find offending peer for orphan: %s (%d).',
+      util.revHex(err.hash), id);
+    return;
+  }
+
+  this.logger.debug(
+    'Punishing peer for sending a bad orphan (%s).',
+    peer.hostname());
+
+  // Punish the original peer who sent this.
+  peer.reject(msg, err);
+};
+
 /**
  * Log sync status.
  * @private
@@ -2402,23 +2463,21 @@ Pool.prototype.switchSync = co(function* switchSync(peer, hash) {
  */
 
 Pool.prototype.logStatus = function logStatus(block) {
-  if (this.chain.total % 20 === 0) {
+  if (this.chain.height % 20 === 0) {
     this.logger.debug('Status:'
       + ' ts=%s height=%d progress=%s'
-      + ' blocks=%d orphans=%d active=%d'
-      + ' target=%s peers=%d jobs=%d',
+      + ' orphans=%d active=%d'
+      + ' target=%s peers=%d',
       util.date(block.ts),
       this.chain.height,
       (this.chain.getProgress() * 100).toFixed(2) + '%',
-      this.chain.total,
       this.chain.orphanCount,
       this.blockMap.size,
       block.bits,
-      this.peers.size(),
-      this.locker.jobs.length);
+      this.peers.size());
   }
 
-  if (this.chain.total % 2000 === 0) {
+  if (this.chain.height % 2000 === 0) {
     this.logger.info(
       'Received 2000 more blocks (height=%d, hash=%s).',
       this.chain.height,
@@ -2504,10 +2563,10 @@ Pool.prototype._handleTX = co(function* handleTX(peer, packet) {
   }
 
   try {
-    missing = yield this.mempool.addTX(tx);
+    missing = yield this.mempool.addTX(tx, peer.id);
   } catch (err) {
     if (err.type === 'VerifyError') {
-      peer.reject(tx, err.code, err.reason, err.score);
+      peer.reject('tx', err);
       this.logger.info(err);
       return;
     }
@@ -4164,6 +4223,7 @@ PoolOptions.prototype._resolve = function resolve(name) {
 
 function PeerList() {
   this.map = {};
+  this.ids = {};
   this.list = new List();
   this.load = null;
   this.inbound = 0;
@@ -4208,6 +4268,9 @@ PeerList.prototype.add = function add(peer) {
   assert(!this.map[peer.hostname()]);
   this.map[peer.hostname()] = peer;
 
+  assert(!this.ids[peer.id]);
+  this.ids[peer.id] = peer;
+
   if (peer.outbound)
     this.outbound++;
   else
@@ -4222,6 +4285,9 @@ PeerList.prototype.add = function add(peer) {
 PeerList.prototype.remove = function remove(peer) {
   assert(this.list.remove(peer));
 
+  assert(this.ids[peer.id]);
+  delete this.ids[peer.id];
+
   assert(this.map[peer.hostname()]);
   delete this.map[peer.hostname()];
 
@@ -4257,6 +4323,16 @@ PeerList.prototype.has = function has(hostname) {
   return this.map[hostname] != null;
 };
 
+/**
+ * Get peer by ID.
+ * @param {Number} id
+ * @returns {Peer}
+ */
+
+PeerList.prototype.find = function find(id) {
+  return this.ids[id];
+};
+
 /**
  * Destroy peer list (kills peers).
  */
diff --git a/lib/protocol/errors.js b/lib/protocol/errors.js
index fb9dd987..8a7ba35f 100644
--- a/lib/protocol/errors.js
+++ b/lib/protocol/errors.js
@@ -50,6 +50,7 @@ function VerifyError(msg, code, reason, score, malleated) {
   this.code = code;
   this.reason = reason;
   this.score = score;
+  this.hash = msg.hash('hex');
   this.malleated = malleated || false;
 
   this.message = 'Verification failure: ' + reason
diff --git a/lib/utils/util.js b/lib/utils/util.js
index 18fa796f..61f8e2a6 100644
--- a/lib/utils/util.js
+++ b/lib/utils/util.js
@@ -7,8 +7,6 @@
 
 'use strict';
 
-/* global gc */
-
 var assert = require('assert');
 var nodeUtil = require('util');
 var os = require('os');
@@ -83,15 +81,6 @@ if (os.homedir) {
 
 util.nop = function() {};
 
-/**
- * Garbage collector for `--expose-gc`.
- * @type function
- * @static
- * @method
- */
-
-util.gc = !util.isBrowser && typeof gc === 'function' ? gc : util.nop;
-
 /**
  * Clone a buffer.
  * @param {Buffer} data