ScottHope:
It has to keep loading up the info for the game if you're always deleting it, doesn't it?
Try not clearing it for a while, see if it improves.
This does not address why clearing his cache improves his meter.
A different option to try is to increase the size of his cache so he doesn't need to clear it often. IIRC, my Firefox cache size was set to 50Mb. In the tools menu select options then advanced and I override automatic cache management and set the cache size on disk to 700Mb. I picked this tip up from one of Infinito's post a long time ago.
Whatever browser you use Chris, I'd bet there is a way to increase the cache size just use Google to find it.