1460981 - multiple redraws make Firefox unusably slow under X Windows

Status: RESOLVED DUPLICATE of bug 1263222

(Core :: Widget: Gtk, defect)

Description

[Ken Olum]

User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:60.0) Gecko/20100101 Firefox/60.0
Build ID: 20180509235650

Steps to reproduce:

Firefox is essentially unusable over X Windows.  It is extremely slow and uses all the bandwidth of a 100Mb network.  To make a simple test, I created a new profile "empty" with default settings, and ran "firefox -P empty about:blank" on Ubuntu 16.04 with DISPLAY set to another machine on which I had allowed direct network connections to the X server.

On the machine running Firefox I ran wireshark to watch all packets being sent over this connection.  It sent 27MB of data, mostly drawing on the screen.  Naturally this takes several seconds to send.  The window is 1280 x 1040 x 24 bits, and thus contains 4MB of data.  So to display the blank window it has written more than 6 times the amount of data stored in the bitmap.

Doing anything more complicated, even displaying a simple page with some basic HTML, will use even larger amounts of data.

This may be related to bug 299727 but in that case the reporter said he had to to various things to get slow behavior, whereas here even the simplest test produces the problem.

Comment 1

[Gingerbread Man]

:smaug it would be appreciated if you could look into this, or at least sort it where it belongs.

Comment 2

[Olli Pettay [:smaug][[e-mail]]]

Let's start from widget, but this might be more like a graphics bug.

Comment 3

[Karl Tomlinson (:karlt)]

I expect this is the same issue as bug 1263222.

Comment 4

[Ken Olum]

As suggested in bug 1263222, I set gfx.xrender.enabled, and that decreased the network usage in the test case above from around 30 MB to around 11 MB, which still seems kind of high, but it's much better than before.