Exceptionally slow javascript performance on one laptop out of a few dozen

Question

I'm working on a web application using a pretty heavy amount of javascript. On the majority of computers (all running IE6...unfortunately), the average document.ready time is about 2 seconds. While this isn't great, it's at least useable.

The problem is one computer has ridiculously slow javascript document.ready times. Something that will take 2 seconds on my computer takes 40 seconds on this one.

I've been trying to find out why and I'm not getting anywhere.

Both computers have the same specs (Intel Core 2 Duo 2GHz, 3 GB of RAM). The slow computer does not have any extra processes running and consistently has a large percentage of System Idle Process (so there's no background processes hogging up the CPU).

On both computers when I load the page and watch the task manager, IE peaks around 50%. They both act the same way (other than the ridiculous time difference)

Does anyone have any idea why this would happen? I've checked everything I can think of and the javascript performance on this one laptop is just terrible.

Edit: Sorry this question is pretty vague. It seems like the two computers are exactly the same in all ways except the drastically different javascript performance. I was hoping someone ran into a similar situation before and knew of something that wasn't obvious to me.

Answer 1

Try profiling with dynatrace ajax edition--it works on IE6.

Answer 2

I have seen this behaviour a number of times on IE6 and the closest I have come to track it is the quicktime plugin.

Answer 3

I finally figured out the problem for anyone interested (or future searches).

Turns out the machines that have the exceptionally slow performance were older unpatched versions of IE6. This is on a corporate intranet so patches stopped for some users because it broke one of the applications they needed. There must have been some sort of memory leak fixed in those patches which is what is causing the crazy slow performance.

Thanks for all the suggestions.