Don't forget that the Amiga demo was probably (optimized) machine code while this demo is in JavaScript. That should add a factor 1000 to 10000 to your estimate. Which sounds correcter, as so much more has happened other than increase of processor frequency.
I'm not referring to any particular demo - many of the animations for Amiga were raytraced animations, but no one claimed it was realtime raytracing. I was referring just to the time it took to render a single frame of an animation.
The images were generated with a standard Amiga with 512K memory. A ray
tracing method was used, which simulates rays of light reflecting within
a mathematically defined scene. Each image requires the calculation of 64,000 light rays and takes approximately 1 hour to generate. An image is compressed to about 10K bytes for storage. Images are expanded in less than 30 milliseconds. The Amiga hold and modify mode is employed so that up to 4096 colors can be displayed at one time.
