As an Example Logic is developed to take advantage of multi core technology:
With and I7 quad core with hyper-threading my system monitor shows 8 cores and Logic uses all of them. Not every software is optimized to take advantage of multi-core systems yet.
in 64 bit mode I can tell Logic how many cores I want it to use to free up CPU power for software instruments.......Its a nice feature.
27" Imac I7 2.93 Ghz, 4 GB ram,
MacBook Pro 2.4 duo, 4 GB ram,
Logic Pro 9, Motu Ultralite Mk III,
Mackie Onyx 1640I, LA 610 Solo,
Event ASP8 Monitors, Motif XS6