Unstable Frame Rate with Powerful PC

[xDD90x]

The game is exhibiting constant stuttering/frame rate drops. It's running at a very choppy 60fps, constantly dipping to 57- 47fps. This is even happening in the pause menu. I don't have this issue in any of my other games. I've had similar issues with one or two older titles in the past, but I managed to fix them by limiting the CPU cores by setting the CPU affinity in Task Manager.

My rig:
i7-12700K
RTX 3080 10GB
32GB DDR4-3200 (2x 16GB)
WD SN850x M.2 NVMe SSD
1TB SanDisk Ultra 2.5" SATA SSD
Windows 11 Pro - optimized/de-bloated.
Display: LG C3 OLED

PC Settings:
Resizable Bar: Enabled
XMP: Enabled
Game Mode: On
Power settings: Ultimate Performance
G-SYNC: Enabled in NCP
Steam Overlay: Disabled
All drivers are up-to-date. Drivers are from manufacturers (not Windows).

The game is installed on the SanDisk Ultra. I'm running it with all settings maxed out except for shadows which are turned down to medium (this is a quirk that is required in order to get the game to display at higher resolutions, as per PCGamingWiki). V-Sync in set to off, which caps the fps at 60. I may have noticed a slight improvement when turning down the draw distance setting, but the stutter was still quite bad.

Steps tried:

• Applied the "4GB Patch" suggested on PCGamingWiki.
  
• Running in compatibility mode for Windows 7 and 8.
  
• Set all graphics settings to low.
  
• Set resolution to 1080p and lower.
  
• Set FPS caps of 60, 59, 58, 57 in NCP.
  
• Forced V-Sync in NCP.
  
• Running in windowed mode set via the game's launcher.
  
• Set Threaded optimization to off in NCP.
  
• Set CPU affinity in Task Manager to 2, 4, 6, 8, 10 cores.
  
• Set CPU affinity with Process Lasso.

Since I built this rig nearly 2 years ago, this is the first game that I have not been able to get to run smoothly, and I've been playing mostly 10+ year old games, including this title's predecessor and all prior Spider-Man games released on PC. I've had to work on most of them to fix issues, but I'm at a loss with this one. I've read through all of the game's Steam forum posts and tried all fixes mentioned there. I've also scoured the web for solutions to no avail.

Please no comments telling me to just not play the game because it's bad. I'm aware of its mediocrity; I played it back when it first released.

Any help would be much appreciated.