On my 5700XT the game runs as expected at 4K Max Settings (45-50FPS)

System information

GPU: RX 5700XT
Driver: mesa-git
Proton version: 4.11.3

I already tried not running things next to ds3. According to GWE and psensor, the GPU and memory usage are always low when the drop happens and the memory usage is low in general.
As I said, I get 60fps most of the time but it drops down randomly and my GPU/CPU usage falls with it(the GPU usage falls as much as the FPS - when the drop is just 10-20fps the GPU usage will be 90-80%, when it's down to 20fps the GPU usage will be around 20%). When I look at the same view again(or just wait 1-2 sec), it gets back to 60fps every time. The amount of FPS drop doesn't seem to be related to the amount of objects on the screen, it can drop down even if I'm looking at a pile of dirt in a closed room with nothing happening around.
I shouldn't run out of anything when I'm running it at 1440p with the lowest settings.
It can't be related to saving either because it never happened when it was saving the game and I have an SSD.
I tried disabling vsync in the nvidia settings and I have the composition settings disabled.

@Trevonn do you have ryzen too?
A lot of windows+ryzen users were complaining on various forums about ds3's performance and they were experiencing huge fps drops even with 6-8GB VRAM at 1080p.

Yeah 2700x but it had no negative impact on performance.

I have an 1800x. Is your GPU utilization 99-100%? 45-50fps seems to be low for the 5700xt. My previous card was a gtx1080(supposed to be slower than yours, had the same issues with ds3 as my current setup and I only changed the GPU a few months ago) and it could hold 60fps most of the time, just like the rtx2080.

Yes and Navi isn't fully optimised on Linux yet that's why it's a bit lower than expected

It looks fine here: https://www.phoronix.com/scan.php?page=article&item=radeon-5700-linuxgl&num=6
Is your GPU utilized properly?

It is specifically the Vulkan driver lacking optimisation. Those are only opengl results. We're getting off topic now though. I'd suggest you close this bug though until you have something more conclusive.

No, we are not off topic at all and I opened this because I don't have anything conclusive.

I'm seeing people mentioning framedrops in the protondb reports: https://www.protondb.com/app/374320

I generated logs: I switched between 2160p, 1440p, low and max settings. I monitored my GPU and the memory utilization was between 31% and 64% while the GPU usage was between 40% and 98% - the two seemed to be tied when increasing/decreasing. None of my CPU cores were utilized more than 70%(peeked at the start only) and 35% was the average. Only GWE, nvidia-settings, ksysguard and steam were running. I didn't see the "DxvkMemoryAllocator: Memory allocation failed" message in the logs either. Could it be a RAM bottleneck? I have two 8GB 2666Mhz single-rank sticks. What are your system specifications(if it's public)?

Update: I have purchased a 2x8gb SR kit with 3200mhz and CL16 and OC'd it in the MOBO - it didn't fix the issue. When the drops happen, neither the GPU nor the CPU is utilized properly.

I know what's the problem: the classic integrated double-buffering vsync. Usually, dbvsysnc will try to "downgrade" the FPS to the previous supported FPS cap when the rate falls by 10-15%(saw this in witcher 3 too). Since DS3's areas are fragmented, the game will load stuff more often which cause minor FPS drops at certain places. I experienced the worst FPS drops at 4k/ultra(down to 17, but I was usually locked to 30 - new shadows are expensive) but when I set my refresh rate to 50hz, the drops disappeared and the average drop was just 2-3 fps(< 10%). Enabling force-composition-pipeline helps too because it interferes with games' vsync.
If there would be a way to disable vsync in games where they don't allow it...
Anyway, I'm closing this because it's an issue in the game.

Thank you, @doitsujin! Now I only get noticeable drops when I enter new areas and only for 1-2 seconds. The places where I consistently lost 30fps became smooth and now I only lose 4-5 fps.

If there would be a way to disable vsync in games where they don't allow it...

DXVK provides one; creating a dxvk.conf next to the game exe with the following contents should disable Vsync:

dxgi.syncInterval = 0

I must say this setting alone managed to solve the most annoying stutters I have been noticing in Assassins Creed: Revelations. They were so bad and intruding that I was about to give up with the game, as no other attempts to fix it was working.

Please consider adding this piece of advice in the wiki, under the Performance section of the Common Issues article.

Indeed, I'm sorry for the misinformation. In fact the stutters continue to be there, and they appear on every new cutscene. But this belongs in its own issue ticket.