Loooks like ill-advised restriction on cvar and setting to the worst possible value, that causes massive fps drops for a lot of people.
r_primitives 0 and 2 are equivalent most times, sometimes ATI drivers internally interpret 0 (default drivers pick choice) as a 1. That's when the fix was to put to 2 manually. in any case 0 which really means 2 for drivers is to dump all the points arrays into gpu in one single go. 1 = forced to do it in chunks and equals massive fps lag. 3 = funky looking screen that drivers dont implement properly, which some people think is walling but it is not, it just looks terrible. As it is with r_primitives forced to 1 and readonly, most people have already noticed that the game looks like a slideshow, dropping from 125fps to 40s or even below.
Also, why wasn't this in changelog?