Dual-boxing my lags fine even triple boxing i have okay lag but when i four box i get lag so bad i can barely move. Heres my PC set up

8800GT 512 MB
4 gigs of DDR2 ram
2.4 Q6600


I alt tab deleted and i exit out of explorer that clears up all the programs redo explorer and i still get extremely bad lag. Whats going on?