219751 2020-12-10 11:44:26 -0800 Efficient low frequency animations 2020-12-16 04:30:45 -0800 1 1 1 Unclassified WebKit Animations Safari Technology Preview Unspecified Unspecified NEW InRadar P2 Normal --- 1 jaffathecake webkit-unassigned dino graouts jer.noble simon.fraser webkit-bug-importer ysuzuki oldest_to_newest 1713638 0 jaffathecake 2020-12-10 11:44:26 -0800 I did some research on how efficient browsers are at animations where not-a-lot happens. https://static-misc-2.glitch.me/low-freq-anims/ I played with the above while monitoring the task manager. The "High frequency animation" shows how much CPU is used on a 60hz (or whatever display frequency) animation. "setTimeout" shows how much CPU is used for a setTimeout-driven animation that updates every 5 seconds. This uses almost no CPU. The rest are CSS/web animations that update infrequently. I'm _really_ impressed with how Safari handles these cases, but there are some opportunities for optimisation. In the following tests: - Discrete values - Mostly same values - Empty animation …Safari seems to use more CPU than necessary, as if it's running a 60hz timer internally. Related Chrome issue: https://bugs.chromium.org/p/chromium/issues/detail?id=1157483 1713761 1 simon.fraser 2020-12-10 16:26:57 -0800 Thanks for the info. Our long-term objective is web-exposed API that allows devs to express what frame rate their animation needs. 1713829 2 jaffathecake 2020-12-10 23:06:01 -0800 Yeah, I think we need that too. I made some notes here https://github.com/whatwg/html/issues/5025 - seems important to allow multiple animations to exist on the same reduced frame rate timeline. I know you've thought about this more than me though, any API ideas? However, I think the unoptimised cases in this test are still worth fixing. Discrete - although a fixed frame rate would work here, it's already expressed in the animation keyframes. Mostly same values - this can't be fixed by a reduced frame rate. I've used this style of animation for a "recording" indicator. Like, a red circle that briefly fades from opacity 0.6 to 1, then back to 0.6, then stays at 0.6 for a few seconds. The fading should be high frequency, but the browser shouldn't run a high frequency timer while values aren't changing. Empty animation - this is an alternative to setTimeout but works with the document timeline timer, and doesn't tick when the document is hidden. I guess you could define this as a 0fps animation? But again this can be inferred. 1714985 3 webkit-bug-importer 2020-12-15 18:10:23 -0800 <rdar://problem/72366315> 1715069 4 graouts 2020-12-16 04:30:45 -0800 I had actually already planned to deal with discrete values, I'm still in the middle of implementing some remaining CSS properties for discrete animations. Mostly same values… that'll require a bit more thinking. Empty animations: that one's easy and I'll file a dedicated bug for this. Note that for steps() we have dedicated logic already.