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A. Performance Tools > Performance Analyzers

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

Looking at Table A-1, it’s clear that there is little overlap in the best practices espoused by each tool. In one sense, this is good—bringing in different perspectives on the performance problem leads to the discovery of new best practices. But this diversity has a more important and unfavorable impact: confusion and fragmentation in the web development community. It’s unclear which set of best practices is best. The choice of tool might be dictated by development environment rather than by the content of the performance analysis.


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