diff --git a/operetta.js b/operetta.js
index 3f51ec6..d7d0f29 100644
--- a/operetta.js
+++ b/operetta.js
@@ -1,6 +1,7 @@
 process.env.NODE_TLS_REJECT_UNAUTHORIZED = "0";
 var cfg = require('./cfg.json');
 
+require('heapdump');
 var gen = require('gen-thread');
 var Imap = require('imap');
 var inspect = require('util').inspect;
@@ -114,7 +115,17 @@ function* main(NEXT, account)
                 });
                 yield msg.once('end', NEXT.cb());
 
-                yield NEXT.throttle(5);
+                // Workaround memory leak in node-imap
+                // TODO: send pull request
+                if (srv._curReq.fetchCache)
+                    delete srv._curReq.fetchCache[seqnum];
+                /*var cached = 0;
+                for (var i in srv._curReq.fetchCache)
+                    cached++;
+                console.log('msg '+seqnum+': '+cached+' in cache');*/
+
+                var [ pgtx, end_transaction ] = yield pg.transaction(NEXT.cb(), function(e) { if (e) throw e; });
+                //yield NEXT.throttle(20);
 
                 var header = Imap.parseHeader(msgrow.headers);
                 for (var i in header)
@@ -144,12 +155,12 @@ function* main(NEXT, account)
                         msgrow.inreplyto = references[references.length-1];
                     else if (references[references.length-1] != msgrow.inreplyto)
                         references.push(msgrow.inreplyto);
-                    var [ err, threadId ] = yield pg.select('MAX(thread_id)').from('messages')
+                    var [ err, threadId ] = yield pgtx.select('MAX(thread_id)').from('messages')
                         .where(pg.sql.in('messageid', references)).val(NEXT.cb());
                     if (err) throw new Error(''+err);
                     if (!threadId)
                     {
-                        var [ err, threadId ] = yield pg.select('MAX(thread_id)').from('messages')
+                        var [ err, threadId ] = yield pgtx.select('MAX(thread_id)').from('messages')
                             .where(new pg.sql.Binary('@>', 'refs', toPgArray([msgrow.messageid]))).val(NEXT.cb());
                         if (err) throw new Error(''+err);
                     }
@@ -157,7 +168,7 @@ function* main(NEXT, account)
                     {
                         try
                         {
-                            var [ err ] = yield pg.update('threads', { msg_count: pg.sql('msg_count+1') })
+                            var [ err ] = yield pgtx.update('threads', { msg_count: pg.sql('msg_count+1') })
                                 .where({ id: threadId }).run(NEXT.cb());
                             if (err) throw new Error(''+err);
                         }
@@ -183,22 +194,24 @@ function* main(NEXT, account)
                     msgrow.flags = msgrow.flags || flagNum[attrs.flags[i].toLowerCase()];
                 msgrow.flags = (msgrow.flags & ~8) | (msgrow.flags & 8 ? 0 : 8); // invert "\seen" (unread) flag
                 console.log(msgrow.time+' '+msgrow.from_email+' '+msgrow.subject);
-                var [ err, id ] = yield pg.raw(
-                    pg.insert('messages', msgrow)+' ON CONFLICT (folder_id, uid) DO UPDATE SET flags=excluded.flags RETURNING id'
+                var [ err, id ] = yield pgtx.raw(
+                    pgtx.insert('messages', msgrow)+' ON CONFLICT (folder_id, uid) DO UPDATE SET flags=excluded.flags RETURNING id'
                 ).val(NEXT.cb());
                 if (err) throw new Error(''+err);
                 msgrow.id = id;
                 if (!msgrow.thread_id)
                 {
-                    var [ err, thread_id ] = yield pg.insert('threads', {
+                    var [ err, thread_id ] = yield pgtx.insert('threads', {
                         first_msg: msgrow.id,
                         msg_count: 1
                     }).returning('id').val(NEXT.cb());
                     if (err) throw new Error(''+err);
                     msgrow.thread_id = thread_id;
-                    var [ err, row ] = yield pg.update('messages', { thread_id: msgrow.thread_id }).where({ id: msgrow.id }).run(NEXT.cb());
+                    var [ err, row ] = yield pgtx.update('messages', { thread_id: msgrow.thread_id }).where({ id: msgrow.id }).run(NEXT.cb());
                     if (err) throw new Error(''+err);
                 }
+
+                end_transaction();
             });
         });
         yield f.once('end', NEXT.cb());
diff --git a/run.sh b/run.sh
index 0b0d182..88f216a 100755
--- a/run.sh
+++ b/run.sh
@@ -1,2 +1,2 @@
 node_modules/.bin/babel operetta.js > operetta.c.js
-nodejs operetta.c.js
+nodejs --max_old_space_size=100 operetta.c.js