Bug 1: I found that my FPS drops significantly on the exit of T10 and through T11 of Sebring. I've never had FPS issues with rF2 before so I tried turning everything down to minimum and I tried all of the tips from here but with no luck. It also seems to not have anything to do with the amount of cars on the server because I had no issues with 50 cars on the server but I had severe FPS problems with 35 cars on the server. The bug gets worse when the sun starts to set ingame. My FPS is capped at 61 (via player.json file) and it drops to around 20-25 when I go through that section which makes the game virtually unplayable for me. I've asked my team mates to check their FPS through a lap of Sebring and they had almost a 50% frame drop through there. My system: Nvidia 750ti, Intel i5-4460, 16gb of RAM Bug 2: In the VEC 12h of Sebring, my team mate got damage through the pits as he hit the safety car parked on the pit exit. After reviewing the replay, it was revealed that he wasn't even close to the safety car, as shown in the picture.
You are probably short of VRAM, I presume your 750 Ti comes with 2 GB, which isn't enough at least not on default graphic settings. Once the VRAM usage goes above what GPU is capable of, you will experience these kind of sporadic stutters. I had the same issue with my old GTX 660, upgraded to GTX 1050 Ti with 4 GB and all problems went away.
It's not sporadic though, it happens every single lap. A couple of friends have 4gb GPU's and they experience the same FPS drop as I do, it's just not dropping below 30 FPS, like in my case.
I noticed the same issue on some other tracks as well in VR. I always make a test run to see how performance is with 30AI before the actually league race I have. On some tracks I noticed with the Performance Overlay for the Oculus Rift that some parts on the track cause extreme performance drops. The headroom just drops from something like 20% to -20% for example at just one short part of the track while the rest of the track would be fine. I wonder what would cause such a drop. Would be great to figure it out, because then those objects that cause those drops could just be deleted. Edit: It is always CPU related to me!
I also have a frame drop in that place, GTX 970, I7 6700k, 16gb Ram. Preparing for VEC 12h i turned off and low some details and i didn't have frame drops during the race. I made the race with pp off, shadows off, environment reflection off, road reflection low and track details high. Hard to know which setting did the trick, this requires some testing.
1080ti here and yes, that section and turn 5 really put load on the GPU. As long as my GPU is at 75-80% on the starting grid, I've enough headroom to make it through 5 and 10 without dropping frames.