Should I do a fresh install?

Hey guys, I purchased my unibody macbook (Intel core 2 duo 2.4 GHz, 4GB ram, 256 SSD, NVIDIA GeForce 9400M 256MB, running 10.7.2) in April of 2009 and have been using it exclusively ever since.

Recently, my computer has begun to slow down quite a bit. Safari hangs on websites, I receive the spinning rainbow more often, the computer shuts down randomly and won't turn back on for hours, etc. I brought the computer into the apple store (it's still covered by applecare until April of 2012), but all of the diagnostics tests came clean. Over the past few weeks, the computer has continued to slow down quite a bit, and I have noticed that my CPU is reaching levels that I haven't seen before. Currently I only have safari open with one tab, but my fans are running at 6000+ RPM and my CPU is peaking a bit over 90 degrees. I looked at my activity monitor and it seems as though the flash plug-in for safari was hogging my CPU usage. I uninstalled that, reinstalled, repaired disk permissions, and restarted my computer, but that hasn't seemed to help since I did it a few days ago.

I know that while my computer isn't exactly new, the processor in particular, I can't seem to feel as though it should be running more efficiently. I've used 159GB of space on my SSD, with around 60GB of that being music and photos.

My question is whether or not doing a fresh install of lion would possibly alleviate this issue. It might not be bad to do spring cleaning, but only if it will possibly help. If I do proceed with a fresh install, is there a way that I can back up just my documents (all on pages), music (all on itunes), and photos (all on iCloud)? I have plenty of time machine backups ranging from when I got the computer to now since I do it every week, but that would restore the computer entirely to those settings.

Suggestions?