http://developer.pidgin.im/attachment/ticket/6241
Screenshot: http://developer.pidgin.im/attachment/ticket/6241/Uber.PNG?format=raw
Only had 1 window open, playing NeverWinter Nights and it goes BOOM with the ram and I start lagging like HELL! LoL
Edit - This is version 2.4.0
You should re-open your ticket at pidgin. We don't recompile pidgin. We use their published method of setting it in portable mode and have a launcher that assists with portability (rewriting paths in settings, allowing people to have data in the proper place to be backed up, etc). So, if there is a memory leak, it's in Pidgin itself.
Sometimes, the impossible can become possible, if you're awesome!
Try updating to 2.4.3 first. See if that helps...if it still does that in portable, try the local version and see if you get the same issue. If you do, then reopen your ticket with that info. I've NEVER seen pidgin do that.