Broadband connections mean nothing for users if your site is slow because it’s poorly coded or thought out.
YSlow evaluates 13 different performance factors and provides a letter grade to each. If for any reason you fail to score a straighth ‘A’, YSlow will provide additional detail to help you solve the problem.
Let’s see how sitepoint.com did:
Overall 64/100 (or a “D”) largely because we don’t use a CDN (Content Delivery Network such as Akamai) nor Entity Tags.
Aside from rating performance factors, YSlow provides useful stats on the loading size of your website, for both brand-new visitors as well as return users who might have portions of your site still in their cache. Here’s how it looks:
Update: All the performance rules are described on Yahoo’s site.