Pretty much this. Add in that in a relatively small project in which you include a few asset store items along with your own code the code build time might be 1

Pretty much this. Add in that in a relatively small project in which you include a few asset store items along with your own code the code build time might be 15s, followed by 15s to launch the editor into play mode; now they're talking about some improvements that might shave a few ms off the time, or a multi-year project (which might actually make a difference); but which probably will be implemented as poorly as everything else they've done. In another year they'll be bored of this performance upgrade, and they'll start something else up. On some of their other attempts: IL2CPP has performance improvements, but it also has issues such as on a select % of laptops it'll just cause a random crashes (even in a very basic project). They tried adding DOTS for graphical improvement rendering a lot of items, but then just sort of semi-abandoned it to work on other tasks. Let's not even get started on them splitting the rendering pipelines.