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> I wonder why anyone would turn ProMotion off considering that 120Hz massively improves responsiveness. The first reason that comes to mind is battery life. T

> I wonder why anyone would turn ProMotion off considering that 120Hz massively improves responsiveness. The first reason that comes to mind is battery life. That's probably the most broadly applicable use case. But also, if I was still doing e.g. frontend web development, I would want to confirm that my css animations looked nice at 60 hz. Edit: My first use case is likely wrong, thank you to replies for reminding me Apple uses adaptive refresh down to 1 hz.

vvillena 3y ago
Isn't battery life a reason to keep it on? The refresh rate will be down to 24hz most of the time.
jwells89 3y ago
macOS is very good at adaptively reducing refresh rate when nothing is happening on screen, with the panel reportedly supporting the full range of 1-120hz so barring badly engineered apps that are permanently pinned at max refresh, the battery impact of keeping ProMotion on is minimal for most use cases.
- Wowfunhappy 3y ago
  Oops, thank you, I completely forgot they were doing the adaptive refresh thing!
- londons_explore 3y ago
  Which raises the question even more why the refresh rate matters during early bootup - surely you could just start with an apple logo and a 1 Hz refresh rate, and then up the rate later during boot when it's time to do some animation...
  - lxgr 3y ago
    Changing the refresh rate makes the screen go blank for a second or so. GP of this thread links to a post arguing that Apple is going out of their way to avoid just that during the boot sequence.
    - londons_explore 3y ago
      Except it doesn't... because during use the dynamic refresh rate changes between 1Hz and 120Hz...
      - lxgr 3y ago
        Well, I can only tell you what happens when you manually change the resolution from 60 Hz to "ProMotion" in macOS. Presumably ProMotion is a specific mode that the display/display controller/... first needs to be set to. If you start out in anything other than that and then switch to it later in the boot process, you'd get that blank screen for a second, and Apple avoids that by writing the startup mode to non-volatile memory. Otherwise they could also just always start out in ProMotion mode – but then you'd get flicker every time you (re)boot into any other mode, like 60 Hz for people who prefer that.
        Wowfunhappy 3y ago
        ...so this is where I'm confused, and where I think GP is confused. Why is there a separate 60 Hz mode that requires blanking the display? Why not just keep dynamic refresh enabled on the panel, and then lock it to updating 60 times per second (which it can do, since it's dynamic) for people who prefer that for whatever reason? What is the difference?
        lxgr 3y ago
        No idea, but if I'd had to speculate: Probably ProMotion activates a quite different internal rendering mode, and fixed 60 Hz mode offers a way to opt out of that? Many applications have a way of synchronizing their drawing loop to the monitor refresh rate, for example; ProMotion must be doing something clever to support them, or they'd just force the refresh rate to 120 Hz. macOS also supports variable refresh rate external monitors these days (via both DisplayPort and HDMI); I'm not sure if that would be labeled "ProMotion" in the display settings, but in any case there are things that can go wrong there, and having a way to opt out of that at the HDMI/DisplayPort signal level (and not just fixing the frame rate at the GPU level while driving the external link under VRR) seems like a good idea.
beebeepka 3y ago
Why would 60 FPS CSS animations look bad on high refresh displays?
- Wowfunhappy 3y ago
  Well the CSS transition wouldn't run at 60 fps, it would run at 120 fps, no? An animation that looks slick at 120 fps might look too fast/slow/complex/whatever on a common 60 hz screen. So if I was still doing this sort of development, I'd prefer to be working on a 60 hz monitor.
  - beebeepka 3y ago
    Aren't CSS animations capped at 60, same as requestAnimationFrame? I've been advocating (and using) high refresh displays for over two decades and I find your reasoning preposterous. Downgrading to crappy 60 Hz monitor for nothing.
    - Wowfunhappy 3y ago
      > Aren't CSS animations capped at 60, same as requestAnimationFrame? Did some quick Googling to make sure I wasn't just out of the loop on this, as far as I can tell they are not the same: https://github.com/whatwg/html/issues/5025 https://github.com/whatwg/html/issues/5025
      - beebeepka 3y ago
        Can you point me to the part confirming your claim? If anything, it's confirming mine that they both are stuck at 60 Hz.
        Wowfunhappy 3y ago
        The link says: > As such, on their 120hz devices, requestAnimationFrame is throttled to 60hz, whereas CSS animations run at 120hz. Please let me know if I am misunderstanding, it has been a few years since I've done this type of work.

vvillena 3y ago

Isn't battery life a reason to keep it on? The refresh rate will be down to 24hz most of the time.

jwells89 3y ago

macOS is very good at adaptively reducing refresh rate when nothing is happening on screen, with the panel reportedly supporting the full range of 1-120hz so barring badly engineered apps that are permanently pinned at max refresh, the battery impact of keeping ProMotion on is minimal for most use cases.

Wowfunhappy 3y ago
Oops, thank you, I completely forgot they were doing the adaptive refresh thing!
londons_explore 3y ago
Which raises the question even more why the refresh rate matters during early bootup - surely you could just start with an apple logo and a 1 Hz refresh rate, and then up the rate later during boot when it's time to do some animation...
- lxgr 3y ago
  Changing the refresh rate makes the screen go blank for a second or so. GP of this thread links to a post arguing that Apple is going out of their way to avoid just that during the boot sequence.
  - londons_explore 3y ago
    Except it doesn't... because during use the dynamic refresh rate changes between 1Hz and 120Hz...
    - lxgr 3y ago
      Well, I can only tell you what happens when you manually change the resolution from 60 Hz to "ProMotion" in macOS. Presumably ProMotion is a specific mode that the display/display controller/... first needs to be set to. If you start out in anything other than that and then switch to it later in the boot process, you'd get that blank screen for a second, and Apple avoids that by writing the startup mode to non-volatile memory. Otherwise they could also just always start out in ProMotion mode – but then you'd get flicker every time you (re)boot into any other mode, like 60 Hz for people who prefer that.
      - Wowfunhappy 3y ago
        ...so this is where I'm confused, and where I think GP is confused. Why is there a separate 60 Hz mode that requires blanking the display? Why not just keep dynamic refresh enabled on the panel, and then lock it to updating 60 times per second (which it can do, since it's dynamic) for people who prefer that for whatever reason? What is the difference?
        lxgr 3y ago
        No idea, but if I'd had to speculate: Probably ProMotion activates a quite different internal rendering mode, and fixed 60 Hz mode offers a way to opt out of that? Many applications have a way of synchronizing their drawing loop to the monitor refresh rate, for example; ProMotion must be doing something clever to support them, or they'd just force the refresh rate to 120 Hz. macOS also supports variable refresh rate external monitors these days (via both DisplayPort and HDMI); I'm not sure if that would be labeled "ProMotion" in the display settings, but in any case there are things that can go wrong there, and having a way to opt out of that at the HDMI/DisplayPort signal level (and not just fixing the frame rate at the GPU level while driving the external link under VRR) seems like a good idea.

beebeepka 3y ago

Why would 60 FPS CSS animations look bad on high refresh displays?

Wowfunhappy 3y ago
Well the CSS transition wouldn't run at 60 fps, it would run at 120 fps, no? An animation that looks slick at 120 fps might look too fast/slow/complex/whatever on a common 60 hz screen. So if I was still doing this sort of development, I'd prefer to be working on a 60 hz monitor.
- beebeepka 3y ago
  Aren't CSS animations capped at 60, same as requestAnimationFrame? I've been advocating (and using) high refresh displays for over two decades and I find your reasoning preposterous. Downgrading to crappy 60 Hz monitor for nothing.
  - Wowfunhappy 3y ago
    > Aren't CSS animations capped at 60, same as requestAnimationFrame? Did some quick Googling to make sure I wasn't just out of the loop on this, as far as I can tell they are not the same: https://github.com/whatwg/html/issues/5025 https://github.com/whatwg/html/issues/5025
    - beebeepka 3y ago
      Can you point me to the part confirming your claim? If anything, it's confirming mine that they both are stuck at 60 Hz.
      - Wowfunhappy 3y ago
        The link says: > As such, on their 120hz devices, requestAnimationFrame is throttled to 60hz, whereas CSS animations run at 120hz. Please let me know if I am misunderstanding, it has been a few years since I've done this type of work.