Are you overclocked?
Are you using swappolube?
Long uptime? Tried rebooting?

Have you got conky installed?
If so what is eating the most cpu and memory?

Have you got battery graph installed?
What are your graphs like?

Htop installed?
What does it output? What's waking the cpu alot?

Quite a vague description of your problem if I'm honest, not much to go on.