Watch beside Image Performance. Its Lazy Loading demo is the page in this film: open the Network panel and scroll.
Every photo on screen is one of the section's own files, and every byte count is that file's real size. The waterfall timings are illustrative, not a measurement.
Perceived stability is one of the design principles in Apple's Human Interface Guidelines (1987).
Photographs: “Lake Mountain Landscape”, Bonnie Moreland; “A tuxedo cat looking at the window”, Punkressph; and “Macro flower wallpaper”, Free Nature Stock; all CC0, from Wikimedia Commons.
The narration is a synthetic voice (ElevenLabs). Timing follows the narration track, so a recorded voice-over can replace it cue for cue using the transcript.
With Reduce Motion turned on in the operating system, the film keeps its fades and drops the sliding motion.
Set in Atkinson Hyperlegible Next and Mono, typefaces the Braille Institute designed for readers with low vision.