Mac speed optimizing software?

I have cable internet, a Airport Extreme base station router, and a MacBook. I have trouble with web pages loading very slowly and other speed issues. Is there some kind of Mac system optimizer that will fix any bottlenecks or problems (if there is any) that are causing slow speeds? I know it could be my internet connection is crappy (I think my cable company sold more bandwidth then they had) but I just want to make sure. I reset Safari often and sometimes it seems to help and other times it doesn't so I don't know if that does anything at all. I also often reset my router and modem with similar results. Anyhoo, is there such a program? If not, how can I find out what is causing the speed issues (modem, router or computer)? Thanx!