I don’t think this can be done, I can see that the selection is disabled.
Try this one; open a shell and run the top command. Start using the proxy and check if any process seems to be taking too much memory or CPU. Also open a new shell and run iptraf and select general interface statistics. Check what is the network utilization while you turn proxy on and off.
Here is my TOP and IPTRAF results with HAVP turn on. Is there anything abnormal with it? I am not too familiar with TOP, but I see three PID’s for HAVP, each one consuming about 32%RAM. Are these separate processes or is it just one?