When clicking on "Play", Unity will reload/re-initializes assemblies and it's causing long delays.
I'm so surprised to find that even an Empty scene will reload all assemblies that are not even part of the scene.
Having a larger project will cause more delays and it's getting too painful to work with every day.
For an example, in my project, with a bunch of Assemblies, it takes about 10 seconds to Start on Empty Scene. This is really ridiculous and I even feel it's embarrassing.
UE's "Play mode" is always Instant no matter how big the project/scene size is. The reason is that the "Edit mode" and "Play mode" is basically the same. While in "Edit mode" the time is stopped except for particle/audio update and rendering. When entering "Play mode", it basically serializes the current state and the time advancement enabled.
In my opinion, Unity should work the same. Unity should reload assemblies only when they are recompiled not every time "Play" is clicked. Right now, it is causing so much pain for me and working with Unity every day.
The "Performance by Default" should start with Editor since everyone can benefit right now without doing anything. One second saved on "Play" can translate to several hours for everyone who is using Unity at the moment.
For me, the biggest benefit of using Unity is the faster compilation time compare to UE4 but it losing all its benefit by having slower Editor in everywhere else, so please take this seriously.
Please find a way to do this and I know it's possible. It may be even a simple fix, who knows, and no one has ever raised the issue.