Created attachment 8899893 [details] blur-stack.txt This example URL  has a blur applied to a div that comprises the entire page, as well as some extra blur applied in some paragraphs, and it also uses opacity. We spend a lot of time painting it, slowing the content process significantly. APZ scrolls smoothly, but it leads to a lot of checkerboarding while the painting is catching up. I'm attaching here a process sample taken with the Activity Monitor on Mac. I don't know if it's the blur filter itself, or a combination of things. I haven't tested with WebRender  https://www.theguardian.com/science/2017/aug/21/solar-eclipse-eye-damage
You need to log in before you can comment on or make changes to this bug.