I just got the mod and it works fine so far. . . And my PC blows goats. It tosses salad like a pro. If my PC were in computer prison, it would be ***** to a Mac, of all things. (Yeah, it sucks that bad.)
Here are my stats: Athlon 3800, 1.5 gb ram, 256 mb geforce 7900.
It's day 35 and I have yet to experience this lag you speak of, apart from a very mild stutter on the map, which is a freeze that lasts for a couple miliseconds. If you can't wait two miliseconds once in a while, play another game. If your lag is a lot worse than that, close other background programs and turn down your settings. If you think you've already done that, you haven't done it right (and I can't look at your computer to figure out how you screwed up) or your computer tosses better salad than mine.
If the former, use your brain. If the latter, get a new PC. Mine is almost a decade out of date and it apparently wipes the floor with yours.