My 2100+ is at about 52 C idle, and 57 C under load. Is this too hot? I have noticed the computer has been running a bit slower than usual lately, is the temp causing this or something else?

That's not too hot. It is not causing your computer to run slower.

are u using the stock cooler? if u want good temperature around the 30s and 40s for your amd.... u should get the volcano9 by thermaltake....i have it ...its very good....and u can adjust the speed with the touch of a button

well i think zenlman is better to cool down the comp. i have one and my average is less then 40 load. i have p4 oc 2.66 thats pretty hot

I use an slk800 with an ocz fan, my cpu temp are never over 37c. i have a xp2100 oc to 2.2.

u should look at some cooling opions,because what u have isnt getting the job done. i run a volcano 10 and have changed the fan and fitted it with a tornado. the 10 is much better than the volcano 9. i have a 9 setting here a paperweight. check out the volcano 12+

I'd leave it alone and spend your time and money doing something else.

That temp is not causing your computer to run slower.