An interesting tradeoff here is that this is less CPU processing but more content to download. The effect is achieved by imposing a blurred image on top of a non-blurred one. Here is the blurred image used in that demo: https://meyerweb.com/eric/css/edge/complexspiral/glassy-ripp...
In many cases this can be the right tradeoff to make. There is also a beauty to its simplicity.
Back then it was just small enough for my ISDN modem. And there are even more images for the headers. But it's also nicely falling back to plain colored backgrounds so the issue of loading the images is not so big. Now I haven't fully checked the frosted glass demo, but shouldn't that even just have impact on the GPU? filter can be accelerated.
Yeah, the filters can be accelerated in most browsers but I believe that is still more battery cost than not having it.