diff --git a/lib/TransactionDb.js b/lib/TransactionDb.js
index 6c1efcd..5eb7d7c 100644
--- a/lib/TransactionDb.js
+++ b/lib/TransactionDb.js
@@ -21,7 +21,7 @@ function spec(b) {
 
   // TODO: use bitcore networks module
   var genesisTXID = '4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b';
-  var CONCURRENCY = 100;
+  var CONCURRENCY = 10;
 
   var MAX_OPEN_FILES    = 500;
   /**
@@ -318,7 +318,7 @@ function spec(b) {
 
       if (o.multipleSpendAttempts) {
 
-        async.each(o.multipleSpendAttempts,
+        async.eachLimit(o.multipleSpendAttempts, CONCURRENCY,
           function(oi, e_c) {
             self.isConfirmed(oi.spendTxId, function(err, is) {
               if (err) return;
@@ -365,7 +365,7 @@ function spec(b) {
       })
       .on('end', function() {
 
-        async.each(ret, function(o, e_c) {
+        async.eachLimit(ret, CONCURRENCY, function(o, e_c) {
             var k = SPEND_PREFIX + o.txid + '-' + o.index;
             db.createReadStream({
               start: k,
@@ -383,7 +383,7 @@ function spec(b) {
               });
           },
           function() {
-            async.each(ret, function(o, e_c) {
+            async.eachLimit(ret, CONCURRENCY, function(o, e_c) {
               self.fillConfirmations(o, e_c);
             }, function(err) {
               return cb(err, ret);