What tasks do you do? I have a 2010 MBPro running ML and it slow has hell for doing any kind of iOS dev work. It used to be pretty fast but Apple's software updates - OS + Xcode have slowed it down considerably.
Also, Mavericks is much snappier than ML from what I've seen so far and makes much better use of RAM.
I've disabled a bunch of things, Spotlight indexing, dashboard, their notification stuff, etc and also moved swap to a new partition, its helped, but still not as snappy as when it was new.
At the moment, I'm weighing my choices .. do I upgrade RAM,SSD or do I get a new one - but then I have to buy apple's expensive ram and cant easily change the SSD in the future.
Tasks: OS X developer.