1531854 - Don't create the hidden window on a normal browsing session

Status: NEW

(Firefox :: General, enhancement, P3)

Description

[:Felipe Gomes (needinfo for replies!)]

On bug 827976, we lazy-fied the hidden window creation, and moved it to happen after first paint (on _delayedStartup). We want to make it to not be used at all on a normal browsing session, but there's still some remaining work to do, which will be tracked here.

The hidden window will remain supported in the platform, because:

• it is necessary on macOS
• we may still allow it to be used on some random features that would be harder to port.

Comment 1

[:Felipe Gomes (needinfo for replies!)]

Here's a talos comparison with a hacky patch to remove the hidden window from about:home (bug 1527213), this allowing this bug to be fixed (not including some other test failures that need to be figured out):

https://treeherder.mozilla.org/perf.html#/compare?originalProject=mozilla-central&newProject=try&newRevision=9a94a97ec620fa95d29f2e81d189d30b2362601a&framework=1&selectedTimeRange=172800

all numbers in the sessionrestore and startup_about_home_paint go down by some 0.5 - 2.0% margin, except startup_about_home_paint on windows10-64-qr, which goes up for some strange reason.