WARNING THIS FIX IS FOR OVERCLOCKERS ONLY for those who have a modern pc with a expensive cpu and get low cycle rates (100%) in the ac bs usage. this is how u fix it or at least improve it. as a bench download road atlanta 50 pits. if that works then youll be able to move to the next step. take the spa 120 pit. (its small track so rendering and data throwing is easy for the computer) keep adding cars in quick race mode till you reach 100% after the 3rd lap. (as the cars separate into their rhythm processing gets easier) after youve found your max just before your 100. then take that quantity to the gring. now you've found your processors sweet spot. (benchmark) now heres the fix. if your motherboard and processor lets you. go in SAVE your bios. on amd processors you can disable your cores i have a thread ripper so i have 2 logic cores per thread so data throwing is easier. corsa only uses 1 "core" for physics and ia problem solving but it its slow because there's not enough clock speed within that core so thats why you get slow mo. if you have a 4gz at 8 cores ac is only using 1/4ghz of that total clock speed. so if you have 8 core make it 6 then clock it to 4.5; or make it 4 then clock to 5ghz the processor wont over heat because its still only using 1 actual core to run a game while the rest of them handle everything else thus making data management more efficient for ac. if you have a decent rig ram wont be a problem because your rams clock speed is already out preforming the cpu anyways. i dont know how kunos calls this a 64 bit game and it only really uses 1 to 2 cores but i hope this works for you guys. as proof when i got ac i have a fx 8350 8core at 4.7ghz and 1200mhz at 8gb. it could do atlanta at half but it only used one core. once i downlocked it so save a little life on it and it ran way slower in ac of course utilizing that one core still. now with the thread ripper and 64gb 3000mhz of ram i can run spa at 81 no slowmo and 101 or 3/4th the speed.(very fun) once i lowered my active cores and set the clock speed higher i could run things smoother. just be careful