[L4D2] Huge FPS drop in L4D1 campaigns after TLS update

[gudvinr]

Since around 2020-10-05 I started to notice severe freezes on L4D1 campaigns.
If I remember right, it was OK when TLS update arrived and only noticed it after a while.

When I play campaigns with survivors from L4D1 (both OG and DLC) FPS drastically drops whenever infected appears.
While standing in areas with low infected population I have 150+ FPS and when at least one infected appears FPS drops to 25 and lower.

For comparison, L4D2 campaigns do not have such issues. I have same 150+ FPS idling and 80-90 during panic events.

Lowering resolution doesn't help. If I change my screen resolution from 2160p to 1080p FPS in idle stays around 300 (capped I suppose) and for L4D1 campaigns it drops to 40 and lower.

Steam System information

video.txt

VideoConfig

``` "setting.cpu_level" "1" "setting.gpu_level" "1" "setting.mat_antialias" "1" "setting.mat_aaquality" "0" "setting.mat_forceaniso" "1" "setting.mat_vsync" "0" "setting.mat_triplebuffered" "0" "setting.mat_grain_scale_override" "0.000000" "setting.mat_monitorgamma" "2.220000" "setting.gpu_mem_level" "2" "setting.mem_level" "2" "setting.mat_queue_mode" "-1" "setting.sdl_displayindex" "0" "setting.defaultres" "3840" "setting.defaultresheight" "2160" "setting.aspectratiomode" "1" "setting.fullscreen" "1" "setting.nowindowborder" "0" ```

[gudvinr]

Last update didn't fix this.
Installation from scratch didn't help either as well as verifying game cache and running without add-ons (and I do not have addons that change models or textures at all).

[gudvinr]

Here's some screenshots:

3840x2160

  

There's also another person who could reproduce this issue. He also has Radeon GPU though.

You can see that when game is lagging "Swap_Buffers" on showbudget graph is going through the roof.
I do not see such thing on L4D2 campaigns for example.

I also noticed that Survivors, Special Infected and L4D1 common infected use DXT1 compression (without alpha) for their appearance textures but L4D2 common infected use DXT5 (since they have alpha channels).
But at the same time Survivors and SI use VertexLitGeneric shader and L4D2 commons use Infected shader for gibs and stuff.
So there is may be an issue with handling DXT1 textures of L4D1 commons inside Infected shader for OpenGL version of the game or some bug in mesa. Either of these can't be solved without Valve involvement.

[gudvinr]

It has been 5 month since issue report and I still can't use half of game content because of this issue. People with whom I play together also limited by that apparently.

[chapuwu]

Hello mate, i had the same problem and it was fixed using vulkan

[gudvinr]

@chapuwu with -vulkan there is #3609 and #3594