[NVIDIA ONLY] vulkan performance regression

[solarmystic]

Gran Turismo HD Concept exhibits a severe performance regression since #7487

Screenshots with MSI Afterburner overlay demonstrating the issue:
Before problematic PR (0.0.8-9594) (locked 60 FPS, lower CPU and GPU usage)

After problematic PR (0.0.8-9595) (47 FPS, drastically increased CPU and GPU usage, staticky audio)

Logs:-
For the unaffected build (0.0.8-9594):-
RPCS3.log.gz

For the affected build (0.0.8-9595):-
RPCS3.log.gz

System Specifications:-
Intel i7-7700 @ 4 GHz
NVIDIA Geforce GTX 1070TI
32 GB DDR4-2400 RAM
Game running on SSD

[solarmystic]

Other games have basically gone up in GPU demands as well since #7487 :-

Demon Souls [BLUS30443]

Before:- locked 60 FPS, with a very smooth frametime graph and lower GPU utlization

After:- still 60 FPS but the frametime graph is more erratic, with 22% higher GPU utilization at the same settings (stock except Write Color Buffers and 4K) with the same scene

Tekken 6 [BLES00635]

Before:- locked 60 FPS, lower GPU utilization

After:- still 60 FPS, but with a higher 31% GPU utilization at the same settings with the same scene

Persona 5 [NPEB02436]

Before:- locked 60 FPS, lower GPU utilization, and a smooth frametime graph

After:- 46 FPS, many frametime spikes evident, 32% higher GPU utilization

[kd-11]

This is an nvidia-only bug, I'm working on a workaround.

[Nerboruto]

unfortunately I had also noticed that on nvidia vulkan performances decreased...

[kd-11]

workaround commited into master.