Video may be cheap, too: h.264 or WebM are relatively low cost on even reasonably modern devices.

To go in the opposite direction, if you wanted to add an option for people fine with large CPU/GPU expenditure (i.e., if this were playing on a dedicated TV in an actual café), it might be fun to add a WebGL canvas and make lofi/vaporwave-inspired effects [0].

[0]: http://hands.wtf/rad

Why would you ever target wasting CPU/GPU when better alternatives are available?

I actually really like this feature when playing music for a whole room on my OLED TV. People like watching the fancy graphics and I get to dodge a tiny little bit of burn in.

You missed the part of better alternatives. I didn't mean to turn off the anim, just switch it to a more efficient method of doing it.

What are the better alternatives?

I'm guessing pre-rendered animations. Better alternative if you're optimizing for performance, but maybe not if we're optimizing for other metrics.

It might be cool.

It might be cool to needlessly spin up a CPU/GPU for no reason other than not being familiar with a more effectient method of doing something? I don't know where you come from, but that's not my definition of cool at all

I would go for videos + options to go with static assets. You could pause background video playback when the tab is not active.

My tests show the tab does not consume much when it is not visible.

Video cheaper than animated gif?

Yeah, lower bandwidth requirements and most computers/all smartphones have dedicated video decoding hardware, especially for h264.

Hinted at with lower bandwidth requirements, but the biggest win with video is their stellar compression. GIFs store every single color value, which is why they get so huge so quick.

GIFs use run length encoding, which usually makes them quite good for pixelly art, but not when you apply a bunch of vfx.

Yep. For example, here is Fill's GIFs site[0], where comic animation on pages represented as video instead of GIF.[1]

    ...
    <video autoplay="" loop="" muted="">
      <source src="/video/aa3d713c20ba03cc3f87b36e9a947857.mp4" type="video/mp4">
    </video>
    ...

[0] https://fill.com.ua/

[1] https://fill.com.ua/gif/zagostrennya