Some later optimizations in the driver may not take older applications (games) into account. Drivers which work with great speed for new games, that use the latest specification, may be sluggish with those that rely on old routines which were current at the time they were made.

I don't know what brg2 is, but not all mods are completely mod-foldered like EB. That means some of the mod files spill into the vanilla installation. EB used to do that until Dol Guldur helped us relocate them for... I think 1.0.

Good luck with the bodyguards.