Is your site delivering pages efficiently?
Two sites can look identical and load seconds apart. Compression, caching headers and server response time decide which one feels instant — and each is set once, at the server or CDN.
Reads the response headers and timing from a sample of your pages. Nothing is stored.
How this check works
Shipwork requests a sample of your pages and reads the delivery headers: whether the HTML is compressed (gzip, brotli or zstd), whether Cache-Control tells browsers and CDNs how long to keep it, whether Vary includes Accept-Encoding, and how long the server took to respond.
Questions
- Why does compression matter?
- HTML compresses 60-80%. An uncompressed page is several times larger over the network, which slows the first byte to first paint for every visitor.
- What should Cache-Control say?
- Static assets want a long max-age with a hashed filename; HTML often wants a short max-age or revalidation. The wrong value means either stale content or no caching at all.
- What is a good time to first byte?
- Under about 200 ms is fast; over 800 ms is worth investigating. It depends on hosting, caching and the work behind the page.