You could check out what files your bot is holding open, using fstat. Get rid of any that aren't Absolutely Necessary. I'm not familiar with the innards of Net::IRC, but you might be able to reduce open file resource use by creating multiple Net::IRC's in one bot, and using a select() over all of them. This could complicate your bot quickly if it does anything besides randomly talk occasionally, though.

Alan

ps I assume you're on some UNIX-like OS since "recompiling the kernel" was mentioned as an option...