Why Graal lags with any window behind it

[protozero]

Why does Graal lag so badly ( Frame rate wise ) when anything, window media player, Xfire, Explorer window, ect. is behind it?

Makes it annoying sometimes when I'm multitasking. Talking to friends, music, homework, surfing web.

Specs

Socket 939 Athlon 64, +3500
1GB Samsung PC3200 ( 2x512, dual channel )
Asus Amberine Motherboard.
ATi X700 Pro, 512 version.
XP Pro, SP 2.

And yes, everything is updated.