1505116 - Consider implementing more style system optimizations for quirks-mode

Status: NEW

(Core :: CSS Parsing and Computation, enhancement, P3)

Description

[Emilio Cobos Álvarez (:emilio)]

As a potential followup to bug 1499170, we could do the following in quirks mode documents:

 * Store the ascii-lowercase version of classes and ids in stylesheets.
 * Store the ascii-lowercase version of id and class on the element.

This enables the following optimizations in quirks mode documents:

 * Using the bloom filter for classes and ids.
 * Fast string comparison / selector-matching.
 * Speed up the stylist rebuilds in the style system.

The most annoying bit is that it requires a separate representation for classList, since that's always case-sensitive.

Per discussion with Boris, it seems worth avoiding the complexity for now, given this isn't really applicable / worth for standards mode pages, but we should have telemetry for which percentage of documents are quirks mode, which change that...

Comment 1

[Emilio Cobos Álvarez (:emilio)]

P3 lacking evidence of greater need for this, I guess.