The Chrome team and Facbook - HTTP Proxy: Isolating server noise from client performance uses a proxy when measuring front end performance changes to get get rid of noise in latency and server performance.
The workflow will be like this:
- Access a URL through the proxy.
- DNS and assets are loaded from Internet.
- The proxy caches all the assets and the DNS lookup.
- The next access will be served locally from the proxy.
WebPageTest is prepared to use WebPageReplay out of the box. Only on Linux & Mac boxes though, I'm not sure if our agent runs Linux I think it's Windows based, so it will be a problem. The Page Replay should run on the same box as the agent. The WebPageReplay uses Dummynet for changing connectivity but I think the Chrome team is working to replace it with TSProxy.
Need to spend some time with WebPageTest and WebPageReplay and see how we can use it (for beta maybe) and in the long run this is something we need to do to be able to measure code changes on the way out to production.