CPU & Memory 100%

Hello,
i’m using rb1000, and when i activated proxy and make a nat redirect to my proxy server i got memory usage 100% and cpu between 80-100% . what i can do to get the memory and cpu free?

configure router to use certain amount of RAM (not unlimited) and do not cache on disk.

http://wiki.mikrotik.com/wiki/Manual:IP/Proxy

Thanks,
i limited the mem cache, and its ok now, but still have a problem with CPU, is that possbile to decrease?

Make sure you’re not providing free proxy access for the entire Internet. Set firewall rules and a catch all deny proxy rule.

Thanks,
still can’t fix the problem with CPU, the load goes 100% after 30 minutes.
P.S The proxy is firewalled.