no not really, but then i've allways had hi spec pc's. it tends to be filters etc that sap your processor power.when you apply the effect(i dont use them that often) it takes an eternity to process, but with modern processors it shouldnt be a problem. i run a intel quad core q6600 @2.3ghz overclocked to 3.1ghz with an added heat sink. it'll process ANYTHING including my electricity bill
mac are better than pc too.
its pretty easy to use too, rather than explain it check this out
http://www.cambridgeincolour.com/tutori ... curves.htm