Use the Editor Iteration Profiler to figure out what specifically is slow:
If it’s related to asset database refresh as you suspect, check if it makes a difference if you use Asset Database v2 (backup your project before activating it):
Enter Play Mode can get really slow as the number of objects in your scene grows ( see this ). Use Unity’s new Configurable Enter Play Mode options to turn off domain and scene reloads. However, this often requires code changes to work properly:
If it’s related to changing code, then it’s very likely the slow-down is caused by domain reloads. Various asset store packages have been identified to poorly implemented some “refresh” related things. The Editor Iteration Profiler should give you some clues in this case.