Originally Posted by
Shred92
Compiling shaders, which is a synchronous process (game rendering halts during the process). Once a shader is compiled it is stored in the Wow.dxvk-cache file so this process is not repeated for this particular shader, but there are a few of them, which means the first time you start the game it's very stuttery for a while.
(Think of a shader as a very small program that generates a discrete visual effect.)
Just to be clear the stuttering shouldn't last that long, probably not hours as I said, so if it keeps happening then your problem lies elsewhere.