Drupal is slow only in IE 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
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.