Vulkan: Performance Issues

[ehw]

Title

This issue affects several games, here are some that I have found that are consistently reproducable.

https://xemu.app/titles/56550021/#Jurassic-Park-Operation-Genesis VU-033 [56550021]
https://xemu.app/titles/4947001f/#Mission-Impossible-Operation-Surma IG-031 [4947001f]
https://xemu.app/titles/49470016/#Superman-The-Man-of-Steel IG-022 [49470016]

Bug Description

There are some games that perform worse while running with the Vulkan backend in comparison to the OpenGL backend, even at native resolution. The performance difference in this case is great enough to cause the games to become unplayable. Despite the low performance, visually the games look identical to the OpenGL backend with no added advantages. This issue seems to occur when there are mostly 3D graphics on the screen, and don't always plague menus or static screens.

Steps to reproduce:
1.) Set the backend to Vulkan. This can be set during or before the game is launched.
2.) All these screenshots are from the very start of the game and can be recreated by just making a new game and going in game, so I won't go into further detail to reproduce unless it's necessary.

All screenshots are with the Vulkan backend. Each screenshot displays the framerate and video statistics for debugging. Make sure if you are going to post to this issue that you post the statistics for both backends in the same scene as well.

Screenshots:
Jurassic Park Operation Genesis:

Mission Impossible Operation Surma:

Superman The Man of Steel:

Expected Behavior

Games running the Vulkan backend should perform identically or better in comparison to the OpenGL backend at least when runnin games at native resolution with no additional accuracy or post processing improvements. The following screenshots show case the same scenes with the OpenGL backend. You can see from the video statistics that the framerate is running much higher and stable and there is a difference in other statistics as well.

Screenshots:
Jurassic Park Operation Genesis:

Mission Impossible Operation Surma:

Superman The Man of Steel:

xemu Version

Version: 0.8.2
Branch: master
Commit: 02d35be
Date: Wed Jan 1 23:02:35 UTC 2025

System Information

CPU: AMD Ryzen 7 5800X 8-Core Processor
OS Platform: Windows
OS Version: 22H2
Manufacturer: NVIDIA Corporation
GPU Model: NVIDIA GeForce RTX 3080/PCIe/SSE2
Driver: 4.0.0 NVIDIA 566.36
Shader: 4.00 NVIDIA via Cg compiler

Additional Context

No response

[SlyCooperReloadCoded]

Add Star Wars: Starfighter Special Edition and Star Wars: Jedi Starfighter to the list of games that have worse performance. Jedi Starfighter already ran at 15 out of 60 FPS on OpenGL on my beefy gaming rig, this lowers it to 5 or 6. Starfighter Special Edition gets a small performance hit ingame, but the menus, which are normally butter-smooth, just break down completely.