Help Starting From New

I have an aluminum and glass macbook with the 2 ghz intel core 2 duo, 4GB of ram, and 160GB hard drive. I have had nothing but problems since I updated my computer to lion. I started out with leopard. My stuff is backed up to my time machine. How would I go about doing a fresh install to start completely over? I'm sick of the slowness and issues I'm having. Any help would be great!

 

So I booted my computer up and held down command+r. I went in and erased everything off of the Macintosh HD. I then installed the iOS lion and the computer seemed pretty fast. I then restored it from a backup on my time machine and it is slower again. It's faster than before I erased the computer but not nearly as fast as when nothing was on the HD. I have a 160GB hard drive and 113GB are free. Any ideas of what is going on?

 

There are no login items setup for me. I deleted all of them awhile ago. As for activity monitor here is a screen shot.