Signal 04 of 09 · Nebula Diagnostic Spec v1.0.0

Load Speed

Does the page become useful quickly enough to keep paid visitors from bouncing?

Decision rule

Main content must reach usable state fast enough on a constrained connection. A run inspects render-blocking behavior, oversized hero media, and late-loading primary content, then reports measured values against the required threshold for the specific finding.

What the engine inspects

  • ·render-blocking resource count
  • ·hero image weight and format
  • ·when primary content becomes visible

How to check it yourself

  1. In DevTools, throttle the network to Fast 3G and reload the page.
  2. Note when the main content becomes usable rather than merely painted.
  3. Inspect the Network tab for render-blocking scripts and oversized hero media; both push usable state past threshold.

The engine automates this inspection and attaches measured evidence to every failing condition. A manual pass is not a substitute for the recorded evidence trail, but it should agree with it.

Pass / fail examples

Pass

Primary content paints early; hero image is sized and compressed for mobile. Within threshold. Clear.

Fail

A multi-megabyte autoplay video delays first meaningful content well past the threshold recorded in the finding. Flagged.