I just skimmed but looking at the ISBoxer file, it looks like you are trying to 5 box with all background on 30fps, and foreground on 60fps, while using a quad core system, I can only guess the RAM is likely DDR2?

I may be off here, but running that much is quite a load on your pc. If you are seeing a 1 sec lag on your repeater regions in more graphic intensive areas, I'd consider myself lucky. What are your game graphic setting on? all low? if not, they should be.