Just for fun (and after reading that it might help gallery use fewer CPU cycles) I wondered if it would have any effect on Invision forums, so I set a couple IPB forums to run through the fastcgi wrapper (one 2.0.4 forum and one 2.1.5 forum). I have no idea if IPB would or could benefit from fastcgi and my question about that over at IPB has yet to be answered, but the wiki suggested that it was a simple matter of commenting out some .htaccess lines to turn it on and off if anything got broken.
Anyway, it seemed to do no harm on my IPB 2.1.5 board but it borked my 2.0.4 forum - clicking on jpg attachments displays image source code instead of photos (in Windows and Mac Firefox, and Safai and Camino - Windows IE works just fine).
Commenting out the .htaccess lines that run php through the wrapper didn't seem to 'undo' the effect as I'd expected. Turning it off at the control panel didn't seem to do anything either. Should I be killing the process(es) from the shell manually? Do I just need to wait an hour or two for them to time out or something?
I'm mostly just curious - I'm planning to upgrade the 2.0.4 to 2.1.6 this weekend so it's not a big deal, but it is is curious. And I immediately found out who on my forums doesn't use IE