What is the Unreal engine startup process?

Hi we are trying to trace down a startup performance issue. We have noticed that after launching an ue4 game that startup time improves dramatically on second launch as opposed to first launch. We were wondering if someone from Epic games could explain how the startup process works with respect to what gets loaded and written out and what gets cached. We were hoping that we could preserve some of the cached data between reboots to improve cold startup performance.

Does anyone know if this is possible?