Trying ZF now with Avast Home 4.8.1229. No noticeable slowdowns or problems as of yet. You can right click the ZF System Tray Icon and choose to open your browser, open private browser, or open unprotected browser. As far as protection however, all the reviews and tests I have read so far on ZF indicate it is anywhere from mediocre to ok, but they all agree it's good as far as an added layer of protection. I'm not sure if it is a keeper, but so far I like it. I also have ThreatFire running and use Windows XP SP3 with Windows Firewall behind a Linksys SPI firewall wireless router.