diff --git a/src/calibre/ebooks/oeb/polish/stats.py b/src/calibre/ebooks/oeb/polish/stats.py
index 476866c368..d4a5c96111 100644
--- a/src/calibre/ebooks/oeb/polish/stats.py
+++ b/src/calibre/ebooks/oeb/polish/stats.py
@@ -11,7 +11,8 @@ import json, sys, os
 from urllib import unquote
 
 from cssutils import parseStyle
-from PyQt4.Qt import (pyqtProperty, QString, QEventLoop, Qt, QSize, QTimer)
+from PyQt4.Qt import (pyqtProperty, QString, QEventLoop, Qt, QSize, QTimer,
+                      pyqtSlot)
 from PyQt4.QtWebKit import QWebPage, QWebView
 
 from calibre.constants import iswindows
@@ -109,6 +110,7 @@ class Page(QWebPage): # {{{
         self.bridge_value = None
         nam = self.networkAccessManager()
         nam.setNetworkAccessible(nam.NotAccessible)
+        self.longjs_counter = 0
 
     def javaScriptConsoleMessage(self, msg, lineno, msgid):
         self.log(u'JS:', unicode(msg))
@@ -116,8 +118,14 @@ class Page(QWebPage): # {{{
     def javaScriptAlert(self, frame, msg):
         self.log(unicode(msg))
 
+    @pyqtSlot(result=bool)
     def shouldInterruptJavaScript(self):
-        return False
+        if self.longjs_counter < 5:
+            self.log('Long running javascript, letting it proceed')
+            self.longjs_counter += 1
+            return False
+        self.log.warn('Long running javascript, aborting it')
+        return True
 
     def _pass_json_value_getter(self):
         val = json.dumps(self.bridge_value)
@@ -130,6 +138,7 @@ class Page(QWebPage): # {{{
             fset=_pass_json_value_setter)
 
     def load_js(self):
+        self.longjs_counter = 0
         if self.js is None:
             from calibre.utils.resources import compiled_coffeescript
             self.js = compiled_coffeescript('ebooks.oeb.display.utils')
diff --git a/src/calibre/ebooks/pdf/render/from_html.py b/src/calibre/ebooks/pdf/render/from_html.py
index 66f9b77b39..2f08e843b0 100644
--- a/src/calibre/ebooks/pdf/render/from_html.py
+++ b/src/calibre/ebooks/pdf/render/from_html.py
@@ -92,7 +92,7 @@ class Page(QWebPage): # {{{
 
     @pyqtSlot(result=bool)
     def shouldInterruptJavaScript(self):
-        if self.longjs_counter < 5:
+        if self.longjs_counter < 10:
             self.log('Long running javascript, letting it proceed')
             self.longjs_counter += 1
             return False
diff --git a/src/calibre/web/jsbrowser/browser.py b/src/calibre/web/jsbrowser/browser.py
index ebecfb05d5..be3174bdb9 100644
--- a/src/calibre/web/jsbrowser/browser.py
+++ b/src/calibre/web/jsbrowser/browser.py
@@ -13,7 +13,7 @@ from threading import current_thread
 
 from PyQt4.Qt import (QObject, QNetworkAccessManager, QNetworkDiskCache,
         QNetworkProxy, QNetworkProxyFactory, QEventLoop, QUrl, pyqtSignal,
-        QDialog, QVBoxLayout, QSize, QNetworkCookieJar, Qt)
+        QDialog, QVBoxLayout, QSize, QNetworkCookieJar, Qt, pyqtSlot)
 from PyQt4.QtWebKit import QWebPage, QWebSettings, QWebView, QWebElement
 
 from calibre import USER_AGENT, prints, get_proxies, get_proxy_info
@@ -83,6 +83,7 @@ class WebPage(QWebPage): # {{{
             result.append(value)
         return ok
 
+    @pyqtSlot(result=bool)
     def shouldInterruptJavaScript(self):
         if self.view() is not None:
             return QWebPage.shouldInterruptJavaScript(self)