I'm inclined to believe what 'mitchellh wrote:
"The Liquid Glass effects are not expensive and anyone claiming they are has no idea how modern GPUs and animation work. Anyone saying it is is either just parroting or is an idiot."
"The Liquid Glass effects are not expensive and anyone claiming they are has no idea how modern GPUs and animation work. Anyone saying it is is either just parroting or is an idiot."
Now that I'm running the iOS 26 beta, I frequently feel animations going slowly or hitching. It's not terrible, but for the first time, I have the feeling that my experience using my iPad would be noticeably improved if I bought a new and more powerful one.
But I guess this makes me an idiot according to Mitchell?
Same thing with Windows. If they just stopped touching it 20 years ago, it would be 50x more responsive now.
I never though HN will be a source for paradoxes.
I always so this with all phones as it saves battery life and feels way snappier to me than some random animation between windows.
I'm struggling to parse that sentence, please elaborate.
(Proofreading in professional publishing is, indeed and to that industry’s great shame, much less of a thing than it used to be, but that’s a different story.)
I have a hard time believing that the GPU is somehow magically energy efficient, so that computing this glass stuff uses barely any energy (talking about battery drain here, not "unused cycles").
But Apple went down that xPU-taxing path a long time ago when they added the blur to views beneath other views (I don't remember what that was called).
Gaussian blurs are some of the most expensive operations you can run, and Apple has been using them for a long time. They’re almost always downscaled because of this.
The first retina iPad (the iPad 3 if I recall) had an awfully underpowered GPU relative to the number of pixels it had to push. Since then, the processors have consistently outpaced pixels.
Your device is easily wasting more time on redundant layout or some other inefficiency rather than Liquid Glass. Software does get slower and more bloated over time, often faster than the hardware itself, not in the ways you might expect.
The GPU has so much headroom that they fit language models in there!
When you have a frosted glass overlay, any pixel change anywhere near the overlay (not just directly underneath) requires the whole overlay to be redrawn, and this is stalled waiting for the entire previous render pass to complete first for the pixels to be valid to read.
The GPU isn't busy in any of this. But it has to stay awake notably longer, which is the worst possible sin when it comes to power efficiency and heat management.
It's true that GPU is itself not busy during a lot of this because it's waiting on pixels, but whatever is preparing the pixels (copying memory) is super busy.
Downscaling is a win not just for the blurring, but primarily the compositing. KDE describes the primary constraint as the number of windows and how many of them need to be blended:
The performance impact of the blur effect depends on the number of open and translucent windows
Note that there are some differences when it's the display server that has to blur general output content on behalf of an app not allowed to see the result, vs. an app that is just blurring its own otherwise opaque content, but it's costly regardless.
(There isn't really anything like on-screen vs. off-screen, just buffers you render to and consume. Updating window content is a matter of submitting a new buffer to show, updating screen content is a matter of giving the display device a new buffer to show. For mostly hysterical raisins, these APIs tend to still have platform abstractions for window/surface management, but underneath these are just mini-toolkits that manage the buffers and hand them off for you.)
https://developer.apple.com/documentation/Metal/customizing-...
The buffers are not that different, it really just means “extra allocation”
(There can be restrictions on which buffer formats and layouts can be used for certain things, scanout being particularly picky, but a regular window can be textured from pretty much any buffer.)
> Now, with the powerful advances in our hardware, silicon, and graphics technologies, we have the opportunity (…)
https://www.youtube.com/watch?v=jGztGfRujSE&t=42s
Coupled with the reports of sluggish performance from the early betas, it’s understandable people would reach the conclusion that the new design pushes the hardware significantly more than before.
a.) Compute-cycles: Some added passes to apply additional shading on top of the completed render, or
b.) Power-consumption: Some added delay in putting components to sleep (reducing CPU/GPU-clock) on every screen update.
Deferred sleep for a portable, battery-powered device because of a longer UI-rendering pipeline can easily add up over time.
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I'd be quite interested to see some technical analysis on this (although more out of technical curiosity than the assumption that there is something huge to be uncovered here...).
There's also the aspect of iOS prioritizing GUI-rendering over other processing to maintain touch-responsiveness, fluidity, etc. Spending more xPU-time on the GUI potentially means less/later availability for other processes.
For sure non-native apps trying to emulate this look (i.e. Flutter) will create a significantly higher impact on the power-profile of a device than a native app.