It is used to reduce lag and stutter in games by pre-compiling a shader cache.
Shaders most re-compile if any of these things change:
the kernel driver
Mesa (or the user-mode part of NVidia's proprietary driver -- but that changes in lockstep with the kernel driver anyway)
the Vulkan loader
DXVK
or the shader code itself.
It is used to reduce lag and stutter in games by pre-compiling a shader cache.
Shaders most re-compile if any of these things change:
https://www.reddit.com/r/linux_gaming/comments/113nzi5/comment/j8rs131/?utm_source=share&utm_medium=web2x&context=3
The shader is also not valid across different GPUs (especially if they are different vendors).