Reproducible: always Steps To reproduce: 0. Make sure e10s is enabled 1. Open https://kangax.github.io/compat-table/es6/ 2. Wait completion of page loading 3. Quickly scroll page left and right with dragging horizontal scrollbar Actual Results: Table header rendering is delayed Expected Results: Table header should be synchronously scrolled with table body Workaround: set apz.drag.enabled to false
This looks like a case of JS updating the table header position, and the JS is lagging behind the async scroll. I don't know if we'll be able to fix this completely but we should at least profile it to see if there's anything we can do to speed up the main-thread operations so it's less laggy.