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macOS Tahoe stuttering / lag while watching YouTube
- Thread starter F23
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Same problems here. I thought it's my Mac and reinstalled everything today, only to realize that it's in fact just Firefox. 
Strangely, it works perfectly with Zen browser (which is also Firefox). Also, the latest Firefox Nightly doesn't seem to have these problems anymore.
Strangely, it works perfectly with Zen browser (which is also Firefox). Also, the latest Firefox Nightly doesn't seem to have these problems anymore.
Project 26 otherwise known as iOS 26 / iPadOS 26 / macOS 26 Tahoe is so fraught with bugs that the experience can best be labeled “Frustrating”.
The protracted amount of time it’s taking to sort out and fix this mess is beyond reasonable.
Yet it just proves that the company is so focused on rather frivolous animations and styling cues, that any consideration regarding productivity and use as a business tool was discarded months ago.
It’s good to be Apple, doing whatever they want, however they want, all at their leisure.
The protracted amount of time it’s taking to sort out and fix this mess is beyond reasonable.
Yet it just proves that the company is so focused on rather frivolous animations and styling cues, that any consideration regarding productivity and use as a business tool was discarded months ago.
It’s good to be Apple, doing whatever they want, however they want, all at their leisure.
And they're even good at that nowadays. They sell 120hz laptop with ProMotion marketing term at premium, then go ahead and ruin it with 15fps Tohoe UI animations.
I am seeing a ~8 second delay before website embedded YouTube videos are being shown. They still start to play though, it just displays a black box in the mean time. This is with Safari 26 on Seqouia, on an M3.
Still OK here on Intel 2019 MBP, radeon 5500M. 1440p60 Youtube videos unplayable on Firefox before but fine now.
Of note however (at least for FF):
1989948 - After I updated to macOS 26, I've noticed video lags (audio keeps playing), especially but not only on YouTube.
NEW (alwu) in Core - Graphics. Last updated 2025-10-21.
bugzilla.mozilla.org
1995638 - Experiment with changing the default thread quality-of-service on macOS
RESOLVED (mstange.moz) in Core - XPCOM. Last updated 2025-10-22.
bugzilla.mozilla.org
Did Apple not tell devs about this?
the solution is to dust off a closteted kept
macbook pro 2012 and play yuotube® video perfectyl!
win-win!
macbook pro 2012 and play tuotube video perfectyl!
win-win!
macbook pro 2012 and play yuotube® video perfectyl!
win-win!
win-win!
the stuttering isnt just on YouTube for me. also happens on GeForce Now