Today we may provide some high level build stats of what widgets are being rebuilt, and we also allow taking profiles with debug widget builds. I'm less familiar with the former, but the latter has the problem that widget self time is not particularly interesting, but has the unfortunate side effect of slowing down the build.

We could create a toggleable "profile" mode which only recorded which widgets are rebuilt, along with information about which regions of the screen are re-pained. In combination with some post processing, this could help users understand what parts of an animation are expensive and could be simplified.

This would be exposed via a service extension toggle and then potentially a devtools UI