Ah. Shader compilation.
So, this happens for everybody and goes away after awhile. Because we're not a game engine, we have no way of telling what shaders we'll need until the game actually needs them, and to make sure we don't break effects or crash, emulation stutters a bit as each shader gets compiled. Once compiled, they stay cached until you either update dolphin or update your GPU driver. Updating either of those invalidates the cache and you have to recompile the shaders.
Some users report that D3D12 is slower for compiling shaders for them.
So, this happens for everybody and goes away after awhile. Because we're not a game engine, we have no way of telling what shaders we'll need until the game actually needs them, and to make sure we don't break effects or crash, emulation stutters a bit as each shader gets compiled. Once compiled, they stay cached until you either update dolphin or update your GPU driver. Updating either of those invalidates the cache and you have to recompile the shaders.
Some users report that D3D12 is slower for compiling shaders for them.