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.