Shaders are typically code run on the GPU to make your game look good. They power lighting and various effects used in rendering the game. Virtually everything uses shaders, and precompiling them can save a lot of resources over having to compute them on the fly, but comes with associated hassles.
You are so spot on with Dead by Daylight. If the survivor chosen to get “rushed down” has a couple specific things in their build or their team can play around it, it becames a huge uphill battle for the killer to get anyone else, but in public games often the teams aren’t coordinated enough, or the survivor chosen isn’t skilled enough to stall it out