Bugzilla

I tried the STR on my Microsoft Surface 3 (also Ubuntu 22.04) which is my "slow machine" (Intel i5-4300U, 2 physical cores, though 4 with hyperthreading). I'm seeing similar results but proportionally slower:
- Subjectively it feels like there's roughly a half-second response-time when I press `i`, in both Firefox and Chrome.
- If I capture a profile in Firefox, I see red jank bars with around 280-350ms duration.
- If I capture a profile in Chrome, I see similar-duration "Long task" bars at the top of the `Main` section, the same area I'm hovering in my screenshot. (e.g. I'm looking at a region right now where it's a 305ms to go from miniplayer to regular, and then 285ms to go back to mini)

(Also, one warning: the *very first* conversion to miniplayer is sometimes extra-long due to some additional resource loads or something; usually this involves YouTube showing a red progress bar at the top of the viewport.  That doesn't always happen, but when it does, it's a bit more time overall to swap modes.  So if you happen to hit that version of the mode-switch the first time, I'd ignore that one for the purposes of this bug; it's sort of an outlier, and I've seen it in Firefox as well as Chrome.)

So: based on my testing (admittedly all on Ubuntu) on fast and slow machines, it seems like Firefox and Chrome are on-par with each other here.

I tried the STR on my Microsoft Surface 3 (also Ubuntu 22.04) which is my "slow machine" (Intel i5-4300U, 2 physical cores, 4 logical cores -- same count as reporter). I'm seeing similar results but proportionally slower:
- Subjectively it feels like there's roughly a half-second response-time when I press `i`, in both Firefox and Chrome.
- If I capture a profile in Firefox, I see red jank bars with around 280-350ms duration.
- If I capture a profile in Chrome, I see similar-duration "Long task" bars at the top of the `Main` section, the same area I'm hovering in my screenshot. (e.g. I'm looking at a region right now where it's a 305ms to go from miniplayer to regular, and then 285ms to go back to mini)

(Also, one warning: the *very first* conversion to miniplayer is sometimes extra-long due to some additional resource loads or something; usually this involves YouTube showing a red progress bar at the top of the viewport.  That doesn't always happen, but when it does, it's a bit more time overall to swap modes.  So if you happen to hit that version of the mode-switch the first time, I'd ignore that one for the purposes of this bug; it's sort of an outlier, and I've seen it in Firefox as well as Chrome.)

So: based on my testing (admittedly all on Ubuntu) on fast and slow machines, it seems like Firefox and Chrome are on-par with each other here.