1303751 - Large etherpad documents become unusable in Firefox

Status: RESOLVED INCOMPLETE

(Core :: DOM: Core & HTML, defect, P3)

Description

[Jeff Muizelaar [:jrmuizel]]

This document is painful to edit in Firefox. It works fine in Chrome.

Here's a profile: https://cleopatra.io/#report=0208026f364e6b67d1982440f9d8ecb361f615d3

Much of the time is spent re-spellchecking the entire document. (bug 1303749)

Comment 1

[Jeff Muizelaar [:jrmuizel]]

The document: https://public.etherpad-mozilla.org/p/wr-plan

Comment 2

[Andrew Overholt [:overholt]]

Does the profile point to a Mac-specific issue (I am probably just reading it improperly but: http://searchfox.org/mozilla-central/source/toolkit/xre/MacApplicationDelegate.mm#99)?

FWIW the editing seems pretty painless on Windows in Aurora.

Comment 3

[Markus Stange [:mstange]]

It's true, the profile shows a lot of Mac event loop overhead in the parent process. It would be nice to find out why for example setWindowsNeedUpdate is called so frequently; it seems to be called for every IPC message that the parent process receives from the content process.

But the real problem in that profile is happening in the content process, and that's almost exclusively bug 1303749.

There's also a bit of slow JS execution in there, for example in this part: https://cleopatra.io/#report=0208026f364e6b67d1982440f9d8ecb361f615d3&javascriptOnly=true&filter=%5B%7B%22type%22%3A%22RangeSampleFilter%22,%22start%22%3A357951,%22end%22%3A359149%7D%5D . 
Though 5.5% of JS execution is in CodeGeneratorShared::generateCompactTrackedOptimizationsMap, which is maybe only called when you're profiling.

Comment 4

[Hsin-Yi Tsai (she/her)[:hsinyi]]

The test case is gone, not much we can do... Please file a new bug with new profiles.