So far it's appears to be working great!
I haven't noticed any erosion of system speed or performance. It's run so quietly in the background that I sometimes forget it's there.
It appears that the free Trial version has most of the important firewall features. Do you use the free version or did you purchase the full version?
I use the freeware version. It does everything I want and expect of it. The pro version is very complex in its use/configuration. I don't see the necessity. I have a home network and cable modem but the pro version is just too unnecessarily complex for my needs. The pro version was designed more for offices and larger networks.