RE: Official - Improving iteration time on C# script changes - Unity Forum
I don’t intend to sound confrontational – this is a very important topic! 
What is the current status of editor iteration performance issues? Specifically, what is the near-term plan and the long-term plan? For the long-term plan, what steps are you taking to absolutely ensure that the proposed technical roadmap is more than conjecture, i.e. a quantified approach to finally putting this issue to rest?
So, we have improved some items, within the reach of the .NET group, by optimizing TypeCache or avoiding to reload MonoScripts at all. It has saved several hundred of milliseconds during a domain reload, and these should be I think in 2022. That being said, we know and acknowledge that it is not solving the regressions that have been going on for years now regarding iteration time. Our group is only managing the C#/.NET part, but iteration time can be heavily impacted by other components (e.g shader compilation, asset database…etc.). The other teams at Unity are working on improving these parts, but I don’t know exactly what is their plan.
From a pure C#/.NET perspective, we know that we can’t solve the iteration time without migrating to CoreCLR and redesigning the “Domain Reload” entirely (More on that in the link below).
That’s why the focus for our group is now mostly about the migration to CoreCLR/MSBuild.
I gave some answers in this thread that should highlight some the challenges and solutions that we are evaluating to improve the situation.