Hereās what I noticed and what worked for me.
Findings:
Whenever you change your graphics settings, reboot the game.
Whenever you modify a car you own, reboot the game.
Why?
Iāve noticed after doing either of the above, my performance tanks to mid 40s for fps.
What I noticed is, if you go back into your settings after doing one of the above noted findings, under basic video youāll see that Nvida DLSS or DLAA has changed to AMD FSR: Off, with no option to change back to the Nvidia DLXX option.
The game runs like crap and looks like crap when this happens.
Restarting the game will set it back to Nvidia DLXX and the performance goes back to 60+ frames and the image quality is much better again.
I also read online that Dynamic Render quality is setting your native resolution:
Medium = 1080
High = 1440
Ultra = 2160
I used medium for render quality, DLAA, shadows medium, Car Texture / Reflections / Mirror are on Ultra, track quality and particle on high.
Maintaining 60fps and good performance, but like I said, rebooting the game pretty much after any settings changes or car modifications.
Hardware:
i7 10700K all core @ 4.6Ghz
RTX 3060TI
32GB DDR4 @ 3200Mhz
Are the restarts still necessary after the patch?
As far as I know the patch came out today, apologies I havenāt played it since the patch so I am only speaking to the issues prior to the patch.
I agree, itās downright laughable.
yupā¦ you still get the random fps drops from one race to another
Yep. Just had it happen. Went from single player at 60fps to multiplayer at 40fps, and back to single player at 25fps.
Iām done.
For everyone thatās done with the game Iāve seen ppl on Steam getting refunds after 20+ hours of play time since itās so buggedā¦ just fyi for anyone on PC
I just tested after the patch, same issue sadly 
I will NEVER buy another Turn10 title again. How in the world does the second major update make the existing problems WORSE?
The Track disappears MORE often than it did. This is absolutely unacceptable.
I never had frame drops before this update. Ran a couple races no problem then it starts bouncing between 30-60fps (locked).
Before it would crash after every race so I guess Iām up to two races nowā¦ thatās pretty cool 
Constant drops in every next race after update. It was before but I could do 10 races with no problem but now after even 1 race at locked 60 V-Sync I have 25-30 fps in second race. If I keep restarting FPS drops to 17-19. And Iām on RTX 3080 1440p with RT ON.
I bet it has something to do with memory leakage because after quitting the race I had a crash and an explanation for the first time in this game that after access to memory adress couldnāt be written to a memory.
Iām not expecting major developments in PC frame rate stability until the middle of 2024, at the earliest.
the bug is marked as fixed
just open a new topic in the troubleshooting hub if you have still the issue after update 2
from Environment - Disappearing / invisible tarmac on PC (1615983):
You can tell by their phrasing of āImprovements to alleviateā that they had no confidence in this. Iām not at all surprised the bug still exists.
Wouldnāt the various crashes on PC come from your version of Windows, Iām on Windows 11 and I donāt have any problems at the moment and you?
Kind of funny that you mention this. I recently got an update, and I swear Forza is running better. Iām just thinking itās a coincidence.
Iām not sure what youāve got going on, but Iām running a Ryzen 5600 (non-x) w/RX 6750 XT 12gb VRAM, 32gb DDR4 3600. Resolution is 1440p and have most options set to high. RT off. Every type of frame generation disabledā¦ just running raw FPSā¦ I rarely see less than 60FPS and have seen a maximum of 140FPS.
So far, thereās only one track that Iāve raced that has disappearing track and itās only in replays where it happens.
still losing 50% fps when making any changes to a car. this game is pathetic, end of
Sorry but this is a joke isnāt it? Every other new Triple A game does not push my rig to the limit at all. Only Forza Motorsport does.
I have a Ryzen 5 3600 X
16 GB RAM OC with XMP Profile
4 TB M2 SSD
RX 7900 XT with 16 GB VRAM.
So nah, the game must be abandonded. That is it.