Clearing the cache

So I have recently noticed a significant reduction in game performance. I thought it was just because I was playing on a larger map, so I started a new game on a tiny map. The game was still choppy on the very first turn, though not has bad, but defenitly worse then a few weeks ago.

The only thing I can think is that maybe I need to clear the cache. I downloaded the new patch and held "shift" while it was starting up to clear it but I didn't notice any difference in performance.

Is there a way I can manually check something to make sure the cache is cleared out?

You can find it:
C:\Documents and Settings\Aleksandar\Application Data\My Games\Sid Meier's Civilization 4\cache

The stuff with Aleksandar is my name so you will have yours.

Ooo and you have to enable to see hidden files,ok.