One very important note to make on the usage of Google PageSpeed Insights or browser based Lighthouse is your location and the effect it has on doing tests on websites on servers located far outside your region.
If you are testing from Bangkok and your client’s server is located in the Netherlands this will negatively influence the score you get using Lighthouse insight. To quote Google Chrome on this
Network interconnects are generally very stable and have minimal impact but cross-geo requests, i.e. measuring performance of a Chinese site from the US, can start to experience a high degree of latency introduced from tier-1 network hops. Applied throttling partially masks these effects with network throttling. Simulated throttling mitigates these effects by replaying network activity on its own.
Hosted PageSpeed Insights
Well, what about the Page Speed Insights itself from their hosted location with Google Developers?
PageSpeed Insights picks the server to run the test from based on your current location. There are four locations:
- Northwestern US (Oregon)
- Southeastern US (South Carolina)
- Northwestern Europe (Netherlands)
- Asia (Taiwan)
NB Web.dev always tests from the US
So also PageSpeed Insights loads from certain regions and so location of you and your computer or test server does matter.
PageSpeed or Lighthouse?
So what should you use? Well, so if you are close to the US or have a solid backbone cable connection to the US use PageSpeed Insights, if not and not far a way from the server you are testing use Lighthouse, if both do not apply you can use Lighthouse with throttling turned on:
Applied throttling partially mitigates these effects by applying a minimum request latency and maximum throughput that masks underlying retries. Simulated throttling mitigates these effects by replaying network activity on its own.
Or you can consider using GTmetrix paid package with servers nearby.