There isn't any good reason why your laptop should be stutterning. I'm running a ghz Athlon 64 with 256mb of PC333 memory and I've had not a single problem running Reason and Ableton yet, everything is silky smooth.
You can always try reinstalling the main programs. If it's the vst's which are causing the problem then it could be the fault of vst's, they do eat up a bit more resources than normal then add to boot many of them aren't by professionals and you add in the possability of it being a badly coded vst going into an infinite loop and trying to turn your pc inside out.