Ah well, if you can't add more mem to speed things up you always can get one of those:
SATA2 DDR2 HyperDrive5
It's unbelievable how fast things work with them drives.
Could testrun one not so long ago ( ...had to give it back, damn ) and yeah, anything that uses a lot of mem/HD-read-writings/HDcache , CAD, video-converting, such things, run fast as hell.
Now yeah, speed has a price, of course.