image.slow
Image is slow to download. Level: Warning.
When it is raised
Raised when the image loads and fetching it took 3 seconds or longer (3,000 ms). The time runs from just before the image request starts until the fetch completes, including any redirects followed and reading the response until it ends or until more than 2,500,000 bytes have arrived, when it stops reading. The message gives the measured time in seconds to one decimal place. The 3-second threshold is the API's own and is not taken from any platform's documentation.
What it does to a shared link
The download took at least 3 seconds from the API's server. A crawler that stops waiting before the download finishes has no picture to show.
How to fix it
- Reduce the file size: compress the image, and use PNG or JPEG at 1200×630 rather than a larger original.
- Serve the image as a stored file from a CDN or static host; an image generated on each request can take longer to arrive.
- Remove redirects between the image URL and the file.
- Re-run the check and confirm the measured time is below 3 seconds.