Measured on the live site, the home page ran at 11 to 21 frames a second while every other page sat in the forties. The page has crystals drifting in the background: fifty-nine of them across its sections, several deliberately out of focus.
A Gaussian blur that moves is drawn again every frame
An SVG filter is rendered to a surface and reused while nothing changes. Animate the element under it and the whole chain runs again — and the chain here is two specular lights, a turbulence grain and four composites.
So the soft shards hold still. A crystal that far out of focus reads as depth whether it drifts or not, and nobody reports seeing it move. The brushed-metal filter is now reserved for crystals above 110 pixels, where it is actually visible. Fields off screen animate nothing at all.
The result
The hero went from 11–21 to 55 frames a second, and every other page to 59–61, with the composition unchanged: the same crystals, the same light, the same focal object still drifting.