Hello @nomisnibor ,
Unfortunately I have not found a definitive solution myself. Even though the compiled cache gets rid of the initial compile during splash screen, there always seem to be something triggering incredibely long shader compilation (or “preparation”, as they now call it) once a project opens up, one way or another - and sometimes the behavior seems to change from one session to another.
And since no official support has been provided here in this thread despite the view count here or in the other thread, there isn’t much one can do imho. So as far as I am concerned, the solution is to only use UE5 to test out single assets and simple BPs inside the thirdperson example, but not using it for anything more complex than that, and not importing any content pack (metahumans, Matrix contents) into it.