IE8 very slow RT 4.0.2

I’ve got an RT 4.0.2 install that the tech staff has been working with.

However we’ve noticed that Internet Explorer 8 is extremely slow when browsing, and can hang completely.

For example, when viewing a ticket with this URL:


IE8 can take up to 90 seconds to retrieve small gifs like this:


It is ONLY IE that does this, and compatibility mode does not work.

So far I’ve tested the following:

IE8 on XP compatibility off - extremely slow, CPU on the box jumps to 60%+ while IE is waiting and the fan kicks in. We really notice this.

IE8 on XP compatibility on - not quite as slow, but still too slow for users’ patience. CPU at 55-60%.

IE8 on Win7 compatibility off - extremely slow. CPU only gets to 50%, but the page is never done. The status bar always says it is waiting for bpslogo.png, even though I can see the Best Practical logo in the lower right.

IE8 on Win7 compatibility on - extremely slow. As above.

Firefox 6.0.2 on XP - very responsive. CPU in the high 40%, but the page load is fast so it is just a spike.

Iceweasel 6.0.2 on Debian Squeeze - very responsive. CPU peaks at 36%.

Except for the IE8/Firefox on XP, these are all different boxes, so the CPU values do not exactly correlate. I put them in just to show that IE8 seems to be working a lot harder than Firefox/Iceweasel.

There are no errors in the Apache log. I can see that IE8 is taking longer to load the pages, but other than that nothing shows up from the web server side.

Similarly, the rt.log is on debug, and all I see are the “rendering attachment…” lines when a Ticket history page is refreshed. Nothing to indicate any difference between an IE8 visit and a Firefox visit.

It seems as if the trouble is mainly with URLs under /rt/Ticket/ that are slow, where the others are not as slow. The history page is slowest. I thought it might be a DB issue, but the fast Firefox results tell me that MySQL is keeping up just fine.

RT 4.0.2 running on Debian Wheezy, kernel 3.0, Apache 2.2.20, MySQL 5.1.58. We’ve got the default theme running. The only customization done to the theme was adding a custom logo into the upper right and lower left corners. Removing the logos doesn’t change response times.

(We’re on Wheezy because I wanted to go to RT 4 before the backport was available, and decided not to move back to Squeeze when it became available)

Has anyone seen this behavior with IE, specifically IE8?