Enable text compression
This means that the URL in question contains text-based resources that are not served with compression.
Why is this important?
Compressing text-based resources allows you to minimize the total bytes sent over the network, with no negative impact to the user. Compression makes text-based resources like HTML, CSS and JavaScript smaller, which means they download more quickly.
What does the Hint check?
This Hint will trigger for any internal URL which contains text-based resources which do not have a content-encoding header set to br, gzip, or deflate.
Sitebulb takes these resources, then compresses them with GZIP to compute potential savings of compressions. If the original size of response is less than 1.4KiB, or if the potential compression savings is less than 10% of the original size, then Sitebulb does not flag it.
How do you resolve this issue?
To solve this issue, you need to enable text compression on your server.
When a browser requests a resource, it will use the Accept-Encoding HTTP request header to indicate what compression algorithms it supports.
If the browser supports Brotli, you should use Brotli because it can reduce the file size of the resources more than the other compression algorithms.
Use GZIP as a fallback to Brotli. GZIP is supported in all major browsers, but is less efficient than Brotli.
Your server should return the Content-Encoding HTTP response header to indicate what compression algorithm it used.
Further Reading
- Enable text compression (Lighthouse documentation)
- Improve HTTP compression with Brotli
- How To Optimize Your Site With GZIP Compression