How do you assign more memory to specific software
In the past few days my iMac (27" 3.06GHz/2x2GB/1TB) has become incredibly slow, no matter what software package I'm using and there is a rather worrying whirring noise in the background which suggests I'm at the limits of my computer's capability/brainpower (unlikely I know!)...
I know on my previous iMac (my current one was purchased in June 2010) you could assign increased memory to specific software packages (eg Quark, Photoshop, Fireworks, etc) to ensure smooth operation but I'm totally at a loss as to where that facility is on this iMac and how exactly I go about changing the current settings - if it's possible at all!
Help please oh wise ones out there!...
iMac, OS X 10.6.8 (Snow Leopard)