The av1 is encoded on your gpu, very little additional load on your cpu. The 4090 you have has 2 dedicated encoders. You just need to record in av1 as well to avoid issues like you had.
That William guy was spamming this combo all week and he was just a massive douchebag about every little thing that didn't go his way. I was battling him for 3rd in one race, I lightly accidentally doored him, and of course he started in and went off about how I was a dirty driver while not acknowledging he was trying to chop me on exit the whole time. So many miserable fucks like him on this game these days.