Preloaded the hero, and the number did not move
The hero image was preloaded at a high fetch priority, which is the standard advice and is genuinely good advice. Largest Contentful Paint came back identical to the millisecond.
The image was never slow to find and never slow to download. It was slow to render, because the element that displays it is created by a component that has not run yet. The four stretches of time below run back to back and add up to the whole measurement, so a saving in one of them has to come out of the total — not out of the next one.
Outside every boundary: Load duration (200ms), Load delay (120ms), Render delay (2100ms; FAILED: the fat one), First byte (180ms), The preload we added, an empty slot for the what shortens render delay Connections: First byte calls Load delay (step 1) Load delay calls Load duration (step 2) Load duration calls Render delay (step 3) The preload we added controls Load delay — shortens this one what shortens render delay controls Render delay (step 4)