[Feature Request] Performance Profiling Tools

[kevinschaich]

React & Chrome devtools have a number of profiling tools to help debug performance issues, e.g. flamegraphs, render charts:

While these are super helpful I realize they're a big undertaking. Even some preliminary bar charts or histograms would be helpful.

Render time is probably not the right metric for us here. Just to brainstorm a few:

• Number of set calls to an atom in the last X milliseconds (how many components are writing to this atom?)
• Data volume in the last X milliseconds (are we setting a HUGE object or binary data every time?)
• Diff volume in the last X milliseconds (are we setting one tiny property on a HUGE object every time?)
• Number of listeners/observer updates in the last X milliseconds (how many components are re-rendering as a result of this atom's change)?

Maybe these are not exactly right but it would be useful to have something.