Reinstalling OSX

Hey everyone.

I've recently been having a lot of trouble with OSX. It's so slow it's almost completely unusable. I've had this install for a couple years now and I figured I would just reformat the computer. This all happened after installing Firefox 4, Little Snitch, and Adobe CS5.5. I have no idea if any of that has anything to do with it but something major changed after that. (The CS5.5 is a trial from Adobe, no piracy here, going to expire soon.)

Anyways, I was wondering, if I just reinstall OSX without reformatting, what will I lose? I have a time machine backup so I'm not too concerned. I'm really not in the mood to reformat and set everything up again, so if I could do a new install and not lose anything that would be amazing. I'm assuming it just rewrites the system files right? Documents and apps would be safe correct?

Thanks!!

 

No I probably don't have enough RAM for Adobe. I only have 2 gigs. The problem is, the computer is dog slow even with nothing running, the computer struggles to launch photo booth. Surfing the internet is a chore now. I hate to say it but it behaves much the same as Windows 7 has for me. Ick. I'm no Windows hater but the OSX I'm used to is blazing fast. MUCH faster than W7.

I thought maybe Adobe was running some crap in the background but I can't find anything. The only other thing I thought of is maybe I set little snitch to block something and now it's constantly trying to connect to something and can't, so it keeps trying, therefore slowing everything to a creeping halt. Problem is, when I check activity monitor nothing looks bad. I have low RAM and CPU usage.

 

Oh, and I have 50 of 250 gigs free. I'm assuming that's good.