Play mode launch is very slow when VS debugger is attached

[shinymerlyn]

I profiled the issue, and it's due to reloading "loose" assets while doing the app domain reload.

When I comment out NodeEditorAssetModProcessor.OnReloadEditor the problem seems to reduce significantly.

This is probably project and machine dependent. In my project it drops from 1:30s to 20s, on my workstation. Other coworkers with less overbuilt machines are probably being affected much worse by this problem. This project has a bunch of SO types attached to node graphs, so it is doing a ton of work during this reload. There's only about 300 graphs with 5-10 objects each, and that seems to be enough to destroy performance. If there's a way to lazy-initialize or lazy-refresh individual items then that would probably be better.

Note that despite the profiler mentioning <MySO>.ctor(), and Unity having some guidance on trying to improve reload time of SOs (https://forum.unity.com/threads/long-waiting-times-in-the-editor-slow-asset-refresh-when-modifying-any-script.981384/), I don't think it is applicable in this case. These SOs are basically just data, with no init code defined.

I think the suggestion on this ticket may also help with this problem, though I don't know all the knock-on effects of that solution: #342