Hacker News Reader

Does anyone know if `contain` can increase paint performance of a webpage meaningfully? It seems like it can prevent unnecessary calls, but I'm wondering if there's any reasonable impact it gives.

View on HN

You'd want to benchmark this yourself, and assume that the impact will probably decrease as browsers progress, but I believe that for very large trees (tables, etc) it can have a fair impact. That said, I'm guessing paints aren't what are usually slowing your page down.

A quick way to validate that is to open up the devtools and run a performance trace. Watch for paint events vs JS code execution and such.

Probably. I've encountered a case where setting `contain` for unrelated reasons noticeably decreased the GPU memory use as reported by the browser: https://phabricator.wikimedia.org/T373066#10096943 (search for "As a bonus"). Wikipedia is pretty light, so in absolute terms it wasn't really meaningful, but I could see that on a more complex site.

Reply on news.ycombinator.com