@craftercis I actually may have stumbled upon a fix:

1. Go into the game menu
2. Go to Options » Video » Quality
3. Scroll to the bottom
4. Set DXR Reflections to Disabled (If 'DXR Shadows' and 'FidelityFX CAS' are enabled, it's fine to leave them.)

Give that a shot and let me know whether it helps at all. 

@bladerunner4077 I actually may have stumbled upon a fix:

1. Go into the game menu
2. Go to Options » Video » Quality
3. Scroll to the bottom
4. Set DXR Reflections to Disabled (If 'DXR Shadows' and 'FidelityFX CAS' are enabled, it's fine to leave them.)

Give that a shot and let me know if it helps at all.

So far I've gotten through 2 hours of gameplay without any stuttering or FPS drops

UPDATE:

I've possibly discovered a fix, but hoping some others can test and verify:

1. Go into the game menu
2. Go to Options » Video » Quality
3. Scroll to the bottom
4. Set DXR Reflections to Disabled (If 'DXR Shadows' and 'FidelityFX CAS' are enabled, it's fine to leave them.)

So far, I've been able to play for 2 hours without a single instance of stutter / FPS dropping.

Crossing my fingers this helps others too!

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Roughly the same issue here!

After the latest patch, I can start the game and play for about 5-8 minutes, and then the framerate drops to 10-20 FPS for no apparent reason, although it does seem to happen more after I open the game menu, access the weapons wheel, or visit a workbench.

~70 hours of game play, and until this last patch, the game has run near-flawlessly.

I've tried lowering my graphics settings, disabling advanced RTX-only features, completely removing & re-installing my graphics drivers, disabling background/startup programs and services, uninstalling the game and re-installing on a new SSD, and even blowing-out all of my system's heatsinks & fans.

The issue persists regardless, and Ubisoft's support so far hasn't been the least bit helpful.

PLEASE fix this Ubisoft! The game is absolutely unplayable because of this.