Low FPS during busy multiplayer sessions | AMD Recording & Instant Replay Features and DCS

[Asphelite]

The following post includes both issue and the solution I have found after testing and troubleshooting for the sake of reproduction, testing and fixing (if possible).

Hey everyone,

For weeks I have been plagued by FPS issues during multiplayer sessions on well known Servers such as BlueFlag, the Growling Sidewinder as well as Graywolfs Grayflag Server, pretty much making the game unplayable near ground, in cockpit or as a whole.
These issues are severe, since the game drops from [my] regular 80-110fps (depending on terrain and surroundings) to 12-30fps. I was extensively trying to find the cause of this issue - especially since, mostly playing online and PvP (DCS competitive too), it meant that there was not much to do for me in game with frames always being this low.
Knowing that AMD never had the best or most stable GPU drivers, I was almost certain that it was related to my drivers - especially since that issue popped up (again) after updating to the newest one a few weeks back.
I tried out different DCS Graphics settings (I think i might have tested out every possible combination by now), clean installing different GPU drivers (with DDU ensuring a true clean install), tried testing it with and without community mods, and so on and so forth.
The most annoying part of this issue is that it felt unreproducible, unpredictable and persistent until I restart my game, only to sometimes realize that the issue comes back after a couple of seconds or minutes after slotting into a plane.

The following findings have been learned with a vanilla DCS install (No Mods, Full Repair etc.).

Trying out different recent AMD drivers did not seem to improve the situation, until I decided to turn off my Radeon ReLive feature.
This feature records the last x seconds for you to save on pressing a Hotkey - an instant replay feature also known as NVIDIA Shadow Play on NVIDIA GPUs. Here's where I found my solution for the issue, with which I hope the Testers or ED Team can investigate if possible.

Issue:
- DCS performance (Single or Multithreaded versions affected alike) drops from regular >80fps to <30fps on busy multiplayer servers (unreliably reproduceable in Single Player)

Fix/Workaround:
Cause: Instant Replay Feature (I can only be sure about AMD's ReLive, as I dont own an NVIDIA card)
Fix 1: Turn off Radeon ReLive feature
Fix 2: Set Video Codec from AVC to HEVC.
Switching from AVC to HEVC also fixes the issue with ReLive enabled.

The issue could also be observed while recording DCS with an AVC-Codec, with the frames dropping to mentioned 12-30fps during recording, only to go up to [my] regular ~100fps - so recording with AVC (ReLive disabled) would still cause the frames to drop.

Now, I know that this is strongly related to AMD and their drivers - however I have not observed any similar behavior in any other game but DCS.
As I am lacking the tools, I can only guess to what the root of the issue is.
I very much hope that posting this bug report including my solution might help out others that have the same issue, as well as get the attention by ED/AMD to maybe check it out. (not going to argue about how useful or sensible an instant replay feature is, thats everyone's own choice and I like saving highlights).

If you need logs, trackfiles or other information that I have not been able to include here, please notify me. Thanks.

With kind regards,
Asphelite


System Specs:
Mainboard: MSI B550 Gaming-Plus
CPU: AMD R5 3600X
RAM: Patriot Viper 32GB@3200mhz CL16 (XMP enabled)
GPU: (Aorus) AMD RX5700XT
PSU: 1000W G80+
OS: Win10

Tested Driver Versions: 23.8.x and newer. (fix was found on 23.8.1; Newest at the time of writing: 23.9.3)

Edited October 18, 2023 by Asphelite

[Asphelite]

DxDiag_18Oct23.txt

One note that I forgot in the post above: Looking up or just rendering the skybox (not being able to see terrain or cockpit), the FPS returns to normal [as can  be seen in the .trk-files. If you need me to record a video of that let me know].
Switching from AVC to HEVC or turning it off during the runtime of DCS also seems to resume to normal FPS.

Adding to the post: Here is a DxDiag report of my system and a log+trk file, one with AVC- and one with HEVC-Codec ReLive Recording enabled whilst slotting on Growling Sidewinders Server, taken just now in DCS-MT.
As mentioned, I cannot reproduce the same issue in single player -  otherwise I would have included those .trk files as well. 

w/ kind regards

HEVC+MT on MP.trk HEVC+MT on MP.log AVC+MT on MP.trk AVC+MT on MP.log

Edited October 18, 2023 by Asphelite

[BIGNEWY]

Thanks for the logs we will take a look