What version did you have before?
I'm not really sure why the TD would be that much more sluggish. Introduced in 2.4 were Events, and internally to implement this there is a new notification system, which will likely increase the amount of CPU the TD utilizes, but I wouldn't expect this to be noticed on anything with a 1GHz processor or faster. Certainly not a 2.2 GHz.
I test the TD on 4 or 5 different PCs , the slowest now being a 2.0GHz Intel processor. I've personally never experienced anything like this. When I was developing 2.0, I saw times close to the ones you are seeing (for opening the bust-out dialog, etc), but that was before the code was optimized, and with tournaments with players ranging from 100 to 500.
Right now I'm trying this with the latest development version (2.5 beta - not yet released). I'm using a pretty fast PC - AMD Athlon 64 X2 Dual, Core Processor 5200+, 2.61 GHz. This is a dual-core processor, but that's really irrelevant since the TD will only use 1 processor.
With a tournament with 200 players in it, I press X to bust a player out, the dialog appears instantly and the player list appears in less than 1 second. With a tournament with 563 players in it, the dialog again appears instantly, and it takes only about 2 and a half seconds for the player list to appear.
I would certainly love to know what is causing the slow-down, but frankly I have no idea. If you notice any change in this, especially if it appears to be in response to something you've done, please let me know. That at least gives me a lead to work with. Right now I just don't have any idea where to go with this.