I have 1 GB of RAM. But that's irrelevant as I'm not going to upgrade my hardware. I was happy with the performance of my machine when I bought it. A hardware upgrade is both unnecessary and impractical for me. So, no, it's not "the answer." My harddrive is 120 GB and I have 10 GB free. I suspect this is the cause of decreased performance. Unfortunately I don't have time to back up everything I need and reinstall OS X. There's too much stuff, fonts, unorganized data, etc. I just want to know if there there any apps that will boost OS performance. Much appreciated.
First off, I agree that you shouldn't have to upgrade your computer to make it work better. If you were fine with the performance before, it should be fine now. However, system updates might have made it slower, I'm not sure, and 1 GB is pretty low (I know I wish I had 2).
But anyway, no application is going to magically improve your performance. You need to delete things you don't need. If you can afford it, buy an external hard disk, or a 4 GB flash drive and move as many files as you can that you don't need often to it. Also, if you don't use all of the applications you have installed, a lot of them can take up surprisingly large amounts of space, so you could also try removing some. The only other suggestion I have is to try Monolingual, which can free up a lot of space. Some people say it can cause problems, though, so try at your own risk.