too much prg in ram

Hi
I 'm gonna use my 4000 on stage
got a lot of sample and prog to use
to be "as fast as possible" i've loaded all my .wav in ram (512 MO)
but i can't load all pgr
now here's my problem
i load the "multi + pgr" of the first song
but then, when i want to load multi + pgr of the next songs...
i cant delete the "pgr of the first song

someone can help me ?

Thanks a lot

not just use one multi wit all your program and smples in that all you have to do is switch with the controller that would be lot easier