Open Bug 1945047 Opened 11 days ago Updated 10 days ago

Small FPS drop after typing for the first time on the console in a new profile on a resource intensive page

Categories

(DevTools :: Console, defect)

Desktop
All
defect

Tracking

(firefox-esr115 unaffected, firefox-esr128 wontfix, firefox134 wontfix, firefox135 wontfix, firefox136 fix-optional)

Tracking Status
firefox-esr115 --- unaffected
firefox-esr128 --- wontfix
firefox134 --- wontfix
firefox135 --- wontfix
firefox136 --- fix-optional

People

(Reporter: atrif, Unassigned)

Details

(Keywords: regression)

Found in

  • 135.0 RC2

Affected versions

  • 136.0a1 (2025-01-30)
  • 135.0 RC2
  • 128.7.0esr

Tested platforms

  • Affected platforms: Windows 10x64, macOS 12, Ubuntu 24
  • Unaffected platforms: none

Preconditions

  • new profile - this happens only once in a new profile

Steps to reproduce

  1. Open https://threejs.org/examples/webgl_instancing_performance.html
  2. Set method to naive
  3. Observe fps still being 60
  4. Open the console (Ctrl + Shift + K)
  5. Input anything such as a single symbol "1"

Expected result

  • Steady FPS.

Actual result

  • Small FPS drop.

Regression range

Additional notes

  • Screen recording: link.
  • There is also a small FPS drop when the console is opened which I don't see on an unaffected build like Firefox 115.19esr.

Alexandru, can you record a profile and share it here? I don't see significant drop in FPS on my machine, but maybe it's because it's quite fast

Flags: needinfo?(atrif)

(In reply to Nicolas Chevobbe [:nchevobbe] from comment #1)

Alexandru, can you record a profile and share it here? I don't see significant drop in FPS on my machine, but maybe it's because it's quite fast

Sure thing: https://share.firefox.dev/4jzYt0x. There is only a ~5 FPS drop on my machine as well but the animation stops for a split second when typing. If more information is needed please let me know.

Flags: needinfo?(atrif)

(In reply to Donal Meehan [:dmeehan] from comment #3)

:nchevobbe any idea on a possible regressor from the pushlog in Comment 0?

not really. It's very unlikely that any of the devtools patches there caused this.

(In reply to Alexandru Trif, Desktop Test Engineering [:atrif] from comment #2)

(In reply to Nicolas Chevobbe [:nchevobbe] from comment #1)
Sure thing: https://share.firefox.dev/4jzYt0x. There is only a ~5 FPS drop on my machine as well but the animation stops for a split second when typing.

Thanks for the profile. I'm not seeing much here, the first evaluation causes us to load some modules, but that's < 20ms. Maybe it's still enough to pause the animation, but that's hard to tell

it does look like the renderer takes more time after the character is typed, which seems to delay the next requestAnimationFrame callback: https://share.firefox.dev/42UCHPt (but I'm not sure how the console evaluation is impacting this)

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