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Performance

How to enable gzip or brotli compression

Text compresses by roughly 70%, so serving it uncompressed is most of your document transferred for no reason, on every request, to every visitor. Every CDN and managed host does it by default — its absence usually means a proxy stripping the header or a misconfigured origin.

What 13x checks

This is rule performance.compression in the public registry: Responses are compressed. It runs on every audit, against the pages we actually fetched, and its result is derived from the response rather than estimated.

Surface
Performance
Score weight
6 of the readiness score
Scope
Runs on every audited page
Applies
To every site

Registry version 2026-07-30. Every rule is published, and the audit is deterministic — the same page produces the same finding every time.

The fix

The same text the audit hands you when this check fails on your own site.

The HTML is served uncompressed at bytes. Text compresses by roughly 70%, so this is most of your document transferred for nothing on every request.

nginx code
gzip on;
gzip_types text/plain text/css application/json application/javascript text/xml application/xml image/svg+xml;
gzip_min_length 256;

# Better, if the module is available
brotli on;
brotli_types text/plain text/css application/json application/javascript text/xml image/svg+xml;

Every CDN and managed host does this by default, so its absence usually means a proxy stripping Accept-Encoding on the way in, or an origin serving directly. Verify:

bash code
curl -sI -H "Accept-Encoding: br,gzip" https://example.com | grep -i content-encoding

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