Bug 111644 – [meta] RecalcStyle accounts for too much time on the main thread

• Status: NEW
• Component: Layout and Rendering

[Eric Seidel (no email)]

[meta] RecalcStyle accounts for too much time on the main thread

In previous of Telemetry using Chromium content_shell on an Android device, we see style recalc taking up as much as 24% of total mainthread time.

https://docs.google.com/spreadsheet/ccc?key=0AlC4tS7Ao1fIdGtJTWlSaUItQ1hYaDFDcWkzeVAxOGc#gid=0
is a very run, but I will add more recent runs in further comments.

This is a meta bug to track planned work of making this take up less main-thread time.  I expect we will take several approaches, including:
- Remove unnecessary recalcs (by deferring the work as much as possible)
- Make parts of recalc faster (for example canShareStyleWith() is very very hot)
- Explore radical ideas such as making style recalc resume-able (resolve only as much of the docuement as is needed to answer a specific query) or computable by parallel threads.