17 bots makes my custom game extremely laggy

[edustu]

I play bot warfare on iw5 pluto and it runs very well, but on iw4x I get 350+ fps on a custom game with no bots, and as soon as I add 17 bots (or even less) it gets extremely laggy and the fps drops to 120sh (feels like 40 though). Is there a fix for it without having to create a dedicated server?? I just want to play it in custom games, thx in advance : )