I don't have anti-virus. It causes way too many problems for me as a developer.

"AHHHHH! NEW UNRECOGNIZED EXE! KILL IT!"
"No, really, I just made it, it's fine."
"TURN OFF CHECKS FOR THIS DIRECTORY OR I'LL KEEP SCREAMING!"
"OK. Turned off."
"AHHH!! WHO ARE YOU AND WHAT IS THAT .EXE!"

40 years and I've never had a virus except in circumstances I expected them (when checking suspect machines in loosely controlled business situations); I'm very disinclined to use anything that annoying.