My MacBook Pro, Core i5, 4 GB RAM, 320 GB HD, has been a real pleasure to use my previous machine was an old PowerBook G4, as slow as you can imagine. Advantages, in my case, are obvious, and, so far, with no issues at all. I don't recommend doing it in previous OSX versions, or if don't want to take risks. It involves disabling the dynamic pager daemon and stop using virtual memory at all in Snow Leopard.
This hint is the result of an experience I tried in the last few days.
