How is the performance of the rest of the app, in general? Does just switching from tab to tab take a much longer time, too?
What I find particularly strange is the loading of tournaments on the Stats tab. There is basically almost nothing faster than loading tournaments, and that is because the app is able to offload the work onto the internal interpreter, so it's very fast. Furthermore, if you've already "refreshed" your tournaments, the TD will simply look at the timestamp of each tournament file to see if the file has been updated since it last loaded it. Therefore, if you press Refresh Tourneys and it loads all 90 tournaments, then immediately press Refresh Tourneys again, it should fly through the list, not actually loading any of them (because they are already loaded).
I have run the software on countless different machines and have never encountered an issue like this. Not being able to replicate the problem makes it difficult to diagnose. But you're not the only one to report this problem. It would seem obvious to me that it is a configuration issue, but I won't swear to it.
Since the TD runs inside of IE, this is where I would look first. You obviously tried updating IE with no luck. How does IE perform otherwise?
The only other thing that I can think of that might directly affect performance would be something that could be auditing Javascript execution, like maybe anti-virus or anti-spyware software, although I don't know of any that I can say definitely does this. But if you have any installed, you might try disabling it and seeing what happens.