Sh*t
Edit1: Updated game. Installed 23.10.2. Still optimizing shaders at every launch.
Edit2: Same fps drops at the same corners.
3 Likes
Donāt even try spa, itās an fps nightmare.
7900xt and 5800x3d build here and even after the last update Iām getting from 120fps at 4k all the way down to 40fps, regardless of any cars on or off screen. I also noticed that the game runs much better and in 3rd person then any other camera mode. Still crashing at every race completion scene now also.
Thatās the worst, I have stopped playing for now on PC because of that crashing at the end of a race. They really need to fix the PC version asap. Having the Series X version to, its way better than the PC counter part, even with two new PC part upgrades.
GPU load drop at the same time.
Ok another day another updateā¦ I appear to have solved all my performance issues 
& No, the update didnāt improve anything.
Hereās the long version, skip to the end if your not interested and read the TLDR.
So, I eagerly awaited the update & once it arrived I was at a loss. No performnce improvements mentioned in the release notes and no performance was recieved ;(
Then, what is this??? an AMD driver update which improvedā¦ nothing Not even the shader caching on every load 
So ignoring all thatā¦ I found a good deal on a 5800x3D & I thought, hmm Iād like an upgrade but Iād rather not have to replace everything right now lets go for it & maybe, as a side benefit I might get some better performance out of Forza.
I bought it, recieveing it today & slung it in the computer. After sorting all the silly issues (tpm, passkeys, raid configs, blah) I tried out Forza and all my issues were gone & I thought, well at least I got some noticable immediate benefitā¦ But not so fastā¦ I realized the clock on my pc was wrong & so headed back to the bios, setting the clock straight and seeing what ever setting had changed.
There were a few small things and then I noticed 4G decoding & Resizable Bar, they were both disabled. Some time ago I had turned these on but not seen any benefit but left them anyhow. Anyways I switched them back on and wnet back to Forza Motorsportā¦ All my issues had returnedā¦ Shock horror :o
So back to the Bios and disabled them againā¦ Back to Forza & all my problems had gone again. Infact I could turn my graphics up and I was getting a rock solid V-sync at 75fps (another thing I had changed before I got the cpu was to swap out the 1920x1080@60hz screen for a 3440x1440@75hz).
So the TLDR isā¦
By Disabling 4G decoding & Resizable Bar in the Bios all my frame drops vanished & I was also able to play at a higher resolution with a perfect frame rate.
Interestingly I just found some one talking about having the same issues in Forza Horizons 5, running through Proton & doing the exact opposite solved their issueā¦ Go figure.
Anyways, hope that helps someone.
2 Likes
What? To be honest i have thought of that but never bothered to try it. Checking now.
Yeap. That worked. Good job mate.
this fixed EVERYTHING 7900xt intel cpu disabling resizable bar & 4g dec in BIOS. NO MORE gpu usage drops!!!
That worked. Good job and Thx. 
AMD 5800X3D with 6800XT / Adrenalin Edition 23.10.2
I was really hoping this would fix my stutter issue but it still persists for me. Iām on Nvidia though, Iāve got a 3080. For me that 4G Decoding setting is tied to the Resizable BAR setting in BIOS, toggling Resizable BAR also toggles 4G. Could you not do the same through the AMD software, though, and disable resizable bar there?
Turning off Rebar and 4G Decoding didnāt work for me. Frames still keep dropping. (Ryzen 5800x, 3070)
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Do you have shader builds every time you start the game with the latest driver for your graphics card?
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Yes. However, Iām sticking with this version.
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Thanks for the advice
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Its BAAAAD 7900XT 5800X3D NVME and 32GB ram and it works like crap. FPS drops everywhere from 150 to 30 and 40 and so on. Its really garbage ! STAY AWAY !
And with update 3.0 they managed to make it run even worse than before.
Iām speechless.
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Downloading now,we shall see.12700,nvme,3090,win11.I was running 4k full/rt 60fps/vsync solid.Lets see if that changes running around Hockenheimring todayā¦ EDIT:SO since the patch I ran some laps on Hakone,before the patch my gpu would be at 93% 60fps/vsync,not itās running at 85% 60fps/vsync and 2 degrees cooler.I am happy about the performance,it seems to be a little bit more efficient.Iām curious if dlss/dlaa works nowā¦ off to test.
7800x3d
7900xtx
32GB RAM @6000
No noticeable performance uplift but perhaps itās more consistent now, one of the corners on Spa usually sees drops to 40fps so Iāll try that out later.
I play at 3440 x 1440p with everything maxed including RT and scale at 150%. Frames are above 90fps.
Obviously performance isnāt an issue for my system but it would be great to remove a few inconsistent points on track and use less power for the same performance
Have you tried 60fps/vsync? I bet youād be rock solid and youāll use less power also your gpu will run much cooler.Since my 4k monitor is 60hz,it works perfect for me,keeps my 3090 60c and under at all times.Since you are around 90fps you arenāt taking advantage of a 120hz vsync,you might want to give 60hz vsync a try m8.
Itās totally random as before, if you try it again I bet you will not get the same results twice. And btw that benchmark is totally broken.