I setup a 1.4 ghz machine with 512 ram and did not encounter any unresponsive behavior. The files compared where heavily differenced, around 280 megs in size. I was able to flip between tabs and change display filters with at most a second of delay. I was able to maximize and minimize and it would paint immediately.

The issue you are running into is more specific with your hardware or software configuration. If you have another test you would like us to try, please let us know.