It checks the HTTP server header of the URL you submit. Once it has gotten a response from the URL it will display all the information it has read from the response headers.
Analyze your CSS to make improvements to the CSS Delivery.
Minimize CSS scripts and files for page speed.
Minify your JS files and scripts to maximize performance.
Check whether your web pages have Gzip compression enabled.
Tests your image delivery so you can improve it.
Reduce your PNG image filesize while keeping quality.
Play with the quality and size of JPEGs to save disk space.
Place multiple images in one image to make fewer requests.
Check how and whether your website files are cached.
Test your web pages for broken links and requests.
How many HTTP requests do your web pages produce?
Encode JPEG and other files into a Base64 string.
Check whether your website has keep-alive settings as enabled.
Remove line breaks from your scripts to save disk space.
Check the HTTP server header of your site.