Debugging with WebPageTest

It's important to establish good habits of testing and performance before, during, and after migrating to Fastly. This allows you to clearly measure the impact of tests and changes to your infrastructure for accurate and informed debugging.

One tool that Fastly recommends for this purpose is WebPageTest.org. WebPageTest provides a free and open source testing tool for deep performance analysis. It is built on browser technology to accurately replicate what your end users encounter when visiting a website.

We recommend using the WebPageTest defaults for basic testing, but keep a few rules in mind:

  • On the Test Settings tab under Advanced Settings, Connection should always be set to Native Connection during initial benchmarks.
  • Two to three test runs may be required before a site is properly caching in Fastly.
  • Using WebPageTest's "Visual Comparison" feature offers an ideal way to A/B test potential changes.
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