I used Zone Alarm happily for a few months, but after upgrading to the latest version I could no longer get internet connection sharing to work.
I've tried Kerio which is easy to use and supports ICS but is also very slow. On my 466mhz Celeron it constantly uses 50-70% of the CPU. I know that's a pretty old computer, but with Zone Alarm running it could easily play MP3s and even DVDs, now sound stutters constantly if I play an MP3 in Winamp or Foobar2k. Disabling Kerio instantly fixes the problem, so I know it's the Firewall that's making the system so slow.
Is there a Firewall that will work with ICS and not slow my computer to a crawl? Preferably one that's easy to use and doesn't cost a fortune.