We have had a lot of feedback about our Drupal site running very slow on a different network. Most of the users on this network use IE (IE6 and IE8), which is causing a huge slowdown compared with Firefox.

However, even in Firefox it is still slower than what we would expect. We have put this down to a local DNS issue (the DNS request is timing out after 2 seconds, then works off another DNS sever. I am assuming this is adding a 2 second latency to all page loads?)

What other problem could be causing a dramatic slow down for Drupal, only in IE?

Site in FF from YSlow:

Empty Cache = Total Weight - 586.2K
Primed Cache = Total Weight - 267.3K
  • 1
    Use something like msfast to analyze the delays.
    – sharpbites
    Commented Apr 12, 2011 at 16:42
  • Installed, however when launching the tool it only gives a "x" in top left to close... everything else is blank
    – WestieUK
    Commented Apr 12, 2011 at 17:23
  • Once an OS has a result for a DNS request, it will cache that. (Unless, of course, the DNS tells it not to...)
    – Arjan
    Commented Apr 12, 2011 at 19:30
  • @Arjan, thanks for that - makes sense.. Will get local IT to look into it..
    – WestieUK
    Commented Apr 13, 2011 at 8:43
  • On Windows, you can see what the response from a specific server is using dnslookup.
    – Arjan
    Commented Apr 13, 2011 at 9:03

3 Answers 3


You could use Speed Tracer. It will help you identify and fix performance problems in your website.

  • Ahh Speed Tracer looks like a great tool thanks. Looking at the reports I can see the "DOMContentLoaded" is taking a stagger 439ms. This has 41% style recalculations. Any idea on what that means and how I can further troubleshoot the cause?
    – WestieUK
    Commented Apr 13, 2011 at 15:01
  • speed tracer is a chrome-only benchmark, I don't see how this helps IE!
    – Alex Weber
    Commented Apr 20, 2011 at 20:46

Javascript is probably your villain.

Especially on IE6 and IE7 and still in IE8, Javascript is MUCH slower than the rest of the world.

Despite not being the most brilliant piece of js ever, drupal.js is harmless. The real harm probably lies a lot of plugins or maybe one or two poorly-coded scripts that perform some kind of expensive DOM lookup or other task that is negligeable in Firefox et al but really slows down IE.


I have seen this problem when I use the jcarousel module. In IE6 and IE7 it takes much longer to load the page.

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