Full Optimization Checklist
|First Byte Time||Applicable Objects||Time to First Byte for the page (back-end processing + redirects)|
|What is checked||The target time is the time needed for the DNS, socket and SSL negotiations + 100ms. A single letter grade will be deducted for every 100ms beyond the target.|
|Keep-Alive||Applicable Objects||All objects that are from a domain that serves more than one object for the page (i.e. if only a single object is served from a given domain it will not be checked)|
|What is checked||The response header contains a "keep-alive" directive or the same socket was used for more than one object from the given host|
|What is checked||Transfer-encoding is checked to see if it is gzip. If it is not then the file is compressed and the percentage of compression is the result (so a page that can save 30% of the size of it's text by compressing would yield a 70% test result)|
|Compress Images||Applicable Objects||JPEG Images|
|What is checked||Within 10% of a photoshop quality 50 will pass, up to 50% larger will warn and anything larger than that will fail.
The overall score is the percentage of image bytes that can be saved by re-compressing the images.
|Use Progressive JPEGs||Applicable Objects||All JPEG Images|
|What is checked||Each JPEG image is checked and the resulting score is the percentage of JPEG bytes that were served as progressive images relative to the total JPEG bytes.|
|What is checked||An "Expires" header is present (and is not 0 or -1) or a "cache-control: max-age" directive is present and set for an hour or greater. If the expiration is set for less 7 days you will get a warning. If the expiration is set for less than 1 hour you will get a failure. This only applies to max-age currently.|
|Use A CDN||Applicable Objects||All static non-html content (css, js and images)|
|What is checked||Checked to see if it is hosted on a known CDN (CNAME mapped to a known CDN network). 80% of the static resources need to be served from a CDN for the overall page to be considered using a CDN. The current list of known CDN's is here|