This might help (994) Compiling Shaders Unreal Engine 5 start up issue FIX FOR MAC IOS - YouTube
The same solution is also mentioned here UE4 "Compiling Shaders" is super slow - Real Time VFX
Tried it, and the start up speed does become fast. However, shaders are compiled when I open an existing project. And the compilation is as slow as before. I try to modify the WorkerProcessPriority value in the BaseEngine.ini configuration file. Then the compilation becomes faster.