diff --git a/src/core/autobridgecalculator.js b/src/core/autobridgecalculator.js
index 53541505..d3848337 100644
--- a/src/core/autobridgecalculator.js
+++ b/src/core/autobridgecalculator.js
@@ -3,6 +3,7 @@
 const _ = require('lodash');
 const assert = require('assert');
 const Amount = require('./amount').Amount;
+const UInt160 = require('./uint160').UInt160;
 const Utils = require('./orderbookutils');
 
 function assertValidNumber(number, message) {
@@ -42,8 +43,6 @@ const NULL_AMOUNT = Utils.normalizeAmount('0');
  */
 
 AutobridgeCalculator.prototype.calculate = function(callback) {
-  this._oldMode = Amount.strict_mode;
-  Amount.strict_mode = false;
 
   const legOnePointer = 0;
   const legTwoPointer = 0;
@@ -60,6 +59,12 @@ AutobridgeCalculator.prototype._calculateInternal = function(
   legOnePointer_, legTwoPointer_, offersAutobridged, callback
 ) {
 
+  // Amount class is calling _check_limits after each operation in strict mode,
+  // and _check_limits is very computationally expensive, so we turning it off
+  // whle doing calculations
+  this._oldMode = Amount.strict_mode;
+  Amount.strict_mode = false;
+
   let legOnePointer = legOnePointer_;
   let legTwoPointer = legTwoPointer_;
 
@@ -70,12 +75,8 @@ AutobridgeCalculator.prototype._calculateInternal = function(
     // of execution so user's browser stays responsive
     const lasted = (Date.now() - startTime);
     if (lasted > 30) {
-      setTimeout(() => {
-        this._oldMode = Amount.strict_mode;
-        Amount.strict_mode = false;
-        this._calculateInternal(legOnePointer, legTwoPointer, offersAutobridged,
-          callback);
-      }, 0);
+      setTimeout(this._calculateInternal.bind(this, legOnePointer,
+        legTwoPointer, offersAutobridged, callback), 0);
 
       Amount.strict_mode = this._oldMode;
       return;
diff --git a/src/core/orderbook.js b/src/core/orderbook.js
index 399f80d2..ed080f78 100644
--- a/src/core/orderbook.js
+++ b/src/core/orderbook.js
@@ -88,7 +88,7 @@ function OrderBook(remote,
   this._gotOffersFromLegTwo = false;
 
   this._waitingForOffers = false;
-  this._offersModifiedAt = 0;
+  this._lastUpdateLedgerSequence = 0;
   this._transactionsLeft = 0;
   this._calculatorRunning = false;
 
@@ -839,29 +839,29 @@ OrderBook.prototype.isBalanceChangeNode = function(node) {
 
 OrderBook.prototype._canRunAutobridgeCalc = function(): boolean {
   return !this._calculatorRunning;
-}
+};
 
 OrderBook.prototype.onTransaction = function(transaction) {
   this.updateFundedAmounts(transaction);
 
 
   if (--this._transactionsLeft === 0 && !this._waitingForOffers) {
-    const lastClosedLedger = this._remote.getLedgerSequence() - 1;
+    const lastClosedLedger = this._remote.getLedgerSequence();
     if (this._isAutobridgeable) {
       if (this._canRunAutobridgeCalc()) {
-        if (this._legOneBook._offersModifiedAt === lastClosedLedger ||
-            this._legTwoBook._offersModifiedAt === lastClosedLedger
+        if (this._legOneBook._lastUpdateLedgerSequence === lastClosedLedger ||
+            this._legTwoBook._lastUpdateLedgerSequence === lastClosedLedger
         ) {
           this.computeAutobridgedOffersWrapper();
-        } else if (this._offersModifiedAt === lastClosedLedger) {
+        } else if (this._lastUpdateLedgerSequence === lastClosedLedger) {
           this.mergeDirectAndAutobridgedBooks();
         }
       }
-    } else if (this._offersModifiedAt === lastClosedLedger) {
+    } else if (this._lastUpdateLedgerSequence === lastClosedLedger) {
       this.emit('model', this._offers);
     }
   }
-}
+};
 
 /**
  * Updates funded amounts/balances using modified balance nodes
@@ -978,7 +978,7 @@ OrderBook.prototype.onLedgerClosed = function(message) {
     return;
   }
   this._transactionsLeft = message.txn_count;
-}
+};
 
 /**
  * Notify orderbook of a relevant transaction
@@ -1080,7 +1080,7 @@ OrderBook.prototype.notify = function(transaction) {
 
   this.emit('transaction', transaction);
 
-  this._offersModifiedAt = this._remote.getLedgerSequence() - 1;
+  this._lastUpdateLedgerSequence = this._remote.getLedgerSequence();
 
   if (!takerGetsTotal.is_zero()) {
     this.emit('trade', takerPaysTotal, takerGetsTotal);
@@ -1370,7 +1370,7 @@ OrderBook.prototype.computeAutobridgedOffers = function(callback = function() {}
   assert(!this._currencyGets.is_native() && !this._currencyPays.is_native(),
     'Autobridging is only for IOU:IOU orderbooks');
 
-  
+
   if (this._destroyed) {
     return;
   }
@@ -1384,8 +1384,6 @@ OrderBook.prototype.computeAutobridgedOffers = function(callback = function() {}
     this._issuerPays
   );
 
-  const lastClosedLedger = this._remote.getLedgerSequence() - 1;
-
   autobridgeCalculator.calculate((autobridgedOffers) => {
     this._offersAutobridged = autobridgedOffers;
     callback();
diff --git a/test/orderbook-autobridge-test.js b/test/orderbook-autobridge-test.js
index 271829fa..bb4bb51a 100644
--- a/test/orderbook-autobridge-test.js
+++ b/test/orderbook-autobridge-test.js
@@ -589,7 +589,7 @@ describe('OrderBook Autobridging', function() {
 
       assert(book._offersAutobridged[2].autobridged);
 
-      done();  
+      done();
     });
 
   });