I like simple solutions, and often forget them while looking for something complicated.

When my cable connection begins to slow down, I try to remember to delete cookies and clean up the internet mess left with temporary files.  Just clicking on the link on this board to delete cookies left by this board often speeds up my connection a great deal.

Next step is to defrag, I just did that after a long time forgetting to do so, It made a difference in speed as well.

I know you probably have already accomplished these steps, but I thought I would drop a reminder if you are like me and often forget such simple steps.