问题
Google provides Speed index for given URL by doing a lighthouse measurement: https://developers.google.com/speed/pagespeed/insights
The data differs a lot from my own measurement. Now my guess is for the mobile page test they use some 4G emulation on a machine located in the US while my testet webserver is located in europe.
Any idea where to find information on the geo location they perform testing from ?
回答1:
Lighthouse uses 'a slow 4G connection'. This choice influences the importance of network speed versus page weight.
From the Lighthouse Github repo:
How does Lighthouse use network throttling, and how can I make it better?
Good question. Network and CPU throttling are applied by default in a Lighthouse run. The network attempts to emulate slow 4G connectivity and the CPU is slowed down 4x from your machine's default speed. If you prefer to run Lighthouse without throttling, you'll have to use the CLI and disable it with the --throttling.* flags mentioned above.
And...
Are results sent to a remote server?
Nope. Lighthouse runs locally, auditing a page using a local version of the Chrome browser installed the machine. Report results are never processed or beaconed to a remote server.
From the web.dev website:
All tests are run using a simulated mobile device, throttled to a fast 3G network & 4x CPU slowdown.
From the web.dev Github repo:
Note: this repo contains the written content for web.dev. The client-side JS and server are not yet open source but we hope to share them soon! bowing_man️
Concluding I would say that web.dev runs Lighthouse in a browser, using local JS, but Google is not very clear about this. My claim can be backed up by people expecting Lighthouse to be able to audit local websites.
来源：https://stackoverflow.com/questions/58394704/google-page-speed-insights-lighthouse-measurement-origin