I'm usually botting 6 chars on one pc and sometimes i zone slow like to direwind or devastation and the fog the entire screen happens to me. I just /unload mq2clip then reload the plugin to get it back to normal.
You could always try lowering your goodfps value, defaults to 22. Play around with the number, and see what works good for you and your system (e.g., /goodfps 12).