The 1200ms was an estimation, but it's definitely closer to 1200ms than it is for 250ms for me. There's definitely a difference in set up here- I'm on a Macbook Pro with an M1 Pro chip.
From a screen recording, I count 53 screen-recorded frames from the apparent start of the animation (which occurs after it's invoked) to desktop widgets becoming transparent (which appears to be the point input is no longer blocked). IINA says the video is 50.582 fps (very strange frame rate?) so that would be ~1050ms.
Of course, that doesn't include any input latency or the display latency, so I also took a video with my phone. I took two trials and I recorded a full 1.08 seconds from key depression to transparent widgets. I did two more with Reduce Motion on and got the exact same time.
I am very curious what your set up is, because I am invested in getting this as close to 8.3 ms as possible.
edit: For comparison, my Linux desktop with a similar experimental set up, this takes about 24ms from key depression to the next desktop becoming visible. The only experimental difference is that I had to switch to the "slow mo" camera to record the difference, and I have a 240hz monitor. The desktop is also considered one of the slower ones (GNOME).
TLDR: It takes 1.08 seconds, on my Macbook, to complete a desktop transition.
Agree. I hate the fullscreen animation so I prefer apps that have a non-native and no animation option such as Ghosty.
I'm also on a M1 Macbook Pro, running Tahoe 26.2.
Not sure why yours is so much slower than mine. Mine is definitely 250 ms long or 15 frames from the time I hit the shortcut.
I used the onscreen keyboard viewer to get visual feedback when the shortcut was pressed and recorded audio so I could hear it being pressed. I even recorded it a second time using OBS to ensure I was at 60 fps and trimmed the whole segment down to just the animation and sure enough, the video is exactly 250 ms long according to IINA.
Also, I don't have any visible delay between pressing the key and the animation starting. The animation starts on the same frame as when the shortcut is recognized by the onscreen keyboard viewer (which is the same time as I hear it being pressed) in the recording. The keyboard delay must be < 16.6 ms.