Bugzilla

I think the hangs get somewhat worse if I scroll down a bunch, e.g. loading FxSiteCompat tweets as far back as 2017.  (Still using a value of 5 for the interruptible reflow env variable.)

Here's a profile after a window-resize after I've populated FxSiteCompat backscroll back through 2017: https://perfht.ml/2pqYmhm

It shows a ~7 second hang which includes two back-to-back ~3 second reflows (the first one is synchronous in a SetWindowDimensions operation, and then after that there's a very short "resize" DOM event, and then there's a refresh driver tick with the second long reflow (2784ms).

I think the hangs get somewhat worse if I scroll down a bunch, e.g. loading FxSiteCompat tweets as far back as 2017.  (Still using a value of 5 for the interruptible reflow env variable.)

Here's a profile after a window-resize after I've populated FxSiteCompat backscroll back through 2017: https://perfht.ml/2pqYmhm

It shows a ~7 second hang which includes two back-to-back ~3 second reflows.  The first reflow is synchronously flushed inside of a SetWindowDimensions operation, and then after that there's a very short "resize" DOM event, and then there's a refresh driver tick with the second long reflow (2784ms).