Vulkan is a graphics API that is used by a lot of games. Left 4 Dead 2 is one of those games. Vulkan can give you a better performance in Left 4 Dead 2. This guide will show you how to run Left 4 Dead 2 on Vulkan.
Step 1:
Download and install the Vulkan RunTime Libraries. You can find them here.
Step 2:
Launch Left 4 Dead 2. Go to the game’s properties by right clicking on the game in your Steam Library.
Step 3:
Click on the "Set launch options…" button.
Step 4:
In the field that appears, type "-novulkan". This will launch the game without Vulkan.
Step 5:
Exit the game’s properties window.
Step 6:
Launch the game. Left 4 Dead 2 should now be running on Vulkan.