Chrome/Chromium is composited slower without "system title bar and borders"

[Daniel van Vugt]

Chrome/Chromium is composited slower without "system title bar and borders".

I had a feeling I could see a difference on my 4K monitor and weak Intel GPU. Enabling "Use system title bar and borders" eliminated stutters and gave me a smoother experience. So now I've taken some measurements from gnome-shell (CLUTTER_SHOW_FPS=1) running Chromium, not stuttering but playing a smoothly rendered video:

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Xorg

Use system title bar and borders ON:

*** X11 screen frame timings over 1.0s: 59.96 FPS, average: 1.0ms, peak: 2.8ms
*** X11 screen frame timings over 1.0s: 60.03 FPS, average: 0.9ms, peak: 2.4ms
*** X11 screen frame timings over 1.0s: 59.99 FPS, average: 1.0ms, peak: 2.2ms
*** X11 screen frame timings over 1.0s: 59.96 FPS, average: 1.3ms, peak: 2.9ms
*** X11 screen frame timings over 1.0s: 59.99 FPS, average: 1.5ms, peak: 2.9ms

Use system title bar and borders OFF:

*** X11 screen frame timings over 1.0s: 56.92 FPS, average: 3.8ms, peak: 5.7ms
*** X11 screen frame timings over 1.0s: 59.94 FPS, average: 3.9ms, peak: 5.5ms
*** X11 screen frame timings over 1.0s: 60.11 FPS, average: 3.7ms, peak: 4.6ms
*** X11 screen frame timings over 1.0s: 59.98 FPS, average: 3.8ms, peak: 4.8ms
*** X11 screen frame timings over 1.0s: 60.00 FPS, average: 3.9ms, peak: 5.4ms

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Xwayland

Use system title bar and borders ON:

*** DP-2 frame timings over 1.0s: 60.00 FPS, average: 0.9ms, peak: 1.6ms
*** DP-2 frame timings over 1.0s: 58.95 FPS, average: 1.2ms, peak: 2.0ms
*** DP-2 frame timings over 1.0s: 60.02 FPS, average: 1.0ms, peak: 2.2ms
*** DP-2 frame timings over 1.0s: 60.00 FPS, average: 1.0ms, peak: 1.6ms
*** DP-2 frame timings over 1.0s: 60.05 FPS, average: 1.0ms, peak: 1.7ms

Use system title bar and borders OFF:

*** DP-2 frame timings over 1.0s: 56.99 FPS, average: 1.4ms, peak: 2.9ms
*** DP-2 frame timings over 1.0s: 58.98 FPS, average: 1.7ms, peak: 2.7ms
*** DP-2 frame timings over 1.0s: 60.00 FPS, average: 1.5ms, peak: 2.2ms
*** DP-2 frame timings over 1.0s: 58.04 FPS, average: 1.5ms, peak: 2.6ms
*** DP-2 frame timings over 1.0s: 59.99 FPS, average: 1.3ms, peak: 2.5ms

[Daniel van Vugt (vanvugt)]

Using CLUTTER_PAINT=damage-region seems to show the difference/problem is the custom window borders being repainted constantly. That doesn't happen when "Use system title bar and borders" is enabled.

[Daniel van Vugt (vanvugt)]

Reported upstream in https://bugs.chromium.org/p/chromium/issues/detail?id=1198080

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.