A.3. Performance Analyzers

YSlow was the first widely used performance “lint” tool. AOL Pagetest, VRTA, and neXpert were released subsequently. Each of these tools has its own set of performance best practices. I’ve aggregated all of these best practices in Table A-1, with an indication of which rules are evaluated by each particular tool. I’ve grouped the best practices into three categories:

• The rules included in High Performance Web Sites

• The best practices described in this book

• Other rules that I haven’t addressed but that are incorporated in at least one of these tools