More info needed. Is this only during scrolling? If so, is there some staging site we can look at that has a lot of content to trigger scrolling?

Is the animation necessary and sufficient to create the problem?

Regardless, this seems more like a scheduling problem.

No this is because we call updateAllLifeCyclePhases outside of beginamainFrame over and over again causing sync painting and compositing updates that are unnecessary. This isn't a scheduling problem.

To repro just scroll down the page a little bit and let the header collapse animations run. You don't need more than a single post.

I'll look into it.

This is the delayed animation that happens after you're done scrolling a space,
right?

I don't see these extra lifecycle class in the traces on ToT Chrome 54, or
Chrome beta. This trace was taken on Chrome 50. Stip could you retry on a newer
Chrome?

Closing this bug due to lack of feedback / not reproducible. I tried again
at ToT just now and found that all the lifecycle updates I checked were due to
BeginMainFrame, hit testing (which correctly stopped before paint), or
forced style recalc (presumably due to script).