I'd been testing with the browser already open but windows would start it up to load the file if it weren't. For me the slowdown starts as soon the button is clicked. The button itself even stays in a depressed state for almost the entire wait. After seeing that you guys aren't getting the same results I pulled out an old test box (XP with IE 6) and it worked fine on that machine so it looks like the problem might be limited to the workstations.

I originally ruled out browser issues and focused on perl/tk as the source of the trouble because removing the perl/tk lines always fixes the problem and it's easy to blame the thing you least understand, but I'm going to have dig into this a little closer.

This could be a problem with the install on the affected machines or even antivirus/security software related...

Thanks once again for the help and the tips!

I'll let you all know what the trouble was if I manage to track the source of this down to anything more interesting than a bad image or a conflict with some obscure internal application.