Also raster.

Removing Android and looking back a year, metrics look in range of reasonability:

https://uma.googleplex.com/p/chrome/timeline_v2/?sid=35b19aeb2e1cc5bf8698b70733afb233

Memory usage on Mac and Windows looks much lower.

Compositing time actually looks like M57 saw a regression, and now we're back to where we were previously.

Paint time has been ticking back up since a big drop in M54, but is still below where it was in M53.

Raster on Mac looks improved in M58 but other platforms are stable.

Looking at just Android over past year:

https://uma.googleplex.com/p/chrome/timeline_v2/?sid=f5260379ab17f0d2b354d16c71796f10

So, Android is really the area where we see progressions in Compositing, Paint Invalidation, and Raster in M58 at 95th pctile currently. But it could also be slower to roll out.

I'm not sure what is actionable here. We could talk with aelias@ to seek insight on Android progressions once more time has elapsed to confirm. He might appreciate being copied on an improvement rather than a regression, especially on a Friday!

Latest per above links, we still see improvement in:

1. Mac/Win/Linux: Picture memory
2. Mac: Raster
3. Android: Compositing, Paint, Paint Invalidation, and Raster

The Android improvements seem like they would be the most valuable to better understand. Change log:

https://chromium.googlesource.com/chromium/src/+log/57.0.2987.0..58.0.3029.0?pretty=fuller&n=10000

~8800 changes. Sifting through could be tough. I made it through about 1/3 looking for paint refs and this is the only change that jumped out at me and it's paint invalidation specific:

https://chromium.googlesource.com/chromium/src/+/ea6322df1cd9d8ce956935dd925fe64ddeda0566

Is it worth digging further?

Mac raster now looks roughly same as previous. Notable metrics change now summarized as:

Android: 18% improvement in Paint Invalidation (Apr 18)
Mac/Win: 20% improvement in Picture Memory (May 2)

These look date- rather than version-based. Will check Finch to see if something specific was enabled/disabled on those dates.

Else could be third party changes, though unusual to see them affect specific platforms to such a degree.

Do not see anything obvious in Finch, though there are many changes around those dates.