I was playing around with overlays for uploading videos. Not for actually in game mind. I was using OBS to help with it but the FPS dropped dramatically in the race. Really annoying because the recorded stuff that came out was not bad.
I genuinely think the CPU is the bottle neck for me on this PC so I might try a few other things before ditching the overlay idea.
Incidentally, to test it, I joined the 2145 fixed F4 race there. Strength of Field was 2.6 and I managed to get up to 10th. Pretty annoyed because I was running in 8th before I spun heading into Luffield. Caught the spin and then hit the gas too hard and the car was almost stable, half spin left me across the track and dropped way back. Noticed a YouTube guy was in that race too and I was right behind him for a bit.