I dont even need 9/10ths of the moto stuff...its all wasted space in my app drawer and system. I go back to stock once in a while to feel the difference, usually cant stand it for more than a day or two. Things are just noticeably more stuttery on stock...could be a placebo effect though
I personally like Motoblur, but thats another issue.
To the OP, load the task manager app, the stock one will do. Look through the list. Does anything stand out as using excessive cpu or ram?