A shader hitch in a loading screen is annoying. A shader hitch during a firefight, a fast camera turn, or a VR interaction is a player-experience problem.
With DirectX 12, Vulkan, and Metal, Unity is no longer dealing with just a shader variant. It is dealing with a Pipeline State Object: the shader plus the rendering state around it, including details such as mesh vertex layout and other GPU state. Every distinct PSO can trigger driver-level compilation.
Your job is simple: move every possible compilation out of gameplay and into a loading phase. The implementation is where it gets painful.
Start here
Profile a development build and look for markers such as Create GPU Program. Turn on shader-compilation logging too. Those two checks tell you whether the hitch is actually shader or PSO work before you lose days debugging the wrong thing.
Do not trust one clean rerun. Unity and GPU-driver caches can hide the problem after the first reproduction. Clear the relevant caches, and sometimes reboot, before declaring a compilation issue fixed.
CEO/Producer translation: newer graphics APIs can be the right product decision, but they also create validation work that does not show up in a feature roadmap. Budget for it.
The full members-only module shows the practical workflow: Graphics State Collections, progressive warm-up, the Addressables trap, cache-miss validation, and the fallback that works when the experimental API does not.