Web Proxy problem

Hi

I have a problem with the webproxy, once i am using it the CPU of my 750G goes to 100% while doing a bandwidth test and also the reply time from speedtest.net goes from 4 ms (without proxy) to 200++ with proxy on.

Is this normal?

I am the only one on this router, i just wanted to test it our, but if i get +200 ms with it it is unusable.

I have on the router version 5.21

Also tested it on a mikrotik 750 with ports in bridge and had the same results with router os 6.0R13.

Is there something can change or help it work better? Thank you