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Google PageSpeed Insights & Lighthouse = Different Results

Looking at the Lab data in Google PageSpeed Insights and then running the same test again in Lighthouse, I am getting different results…

I know field data is based on actual users, but surely if the Lab data is done by running a simulation the results should be the same in both tools?

PageSpeed Insights:

Lighthouse:

One says there’s a big problem, the other says it’s not so bad which makes finding and fixing tricky.

Anyone have any ideas?


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One is run in the cloud while the other is run from your location on the net using your browser. So yes there will be differences just from a network perspective. For a full breakdown on differences review About PageSpeed Insights | Google Developers

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Many thanks for confirming @webdev

Which would you choose to trust the most?

It is not a question of trust. I use both for analysis. I more frequently use lighthouse because I do lots of local development but page speed insights uses a broader data set which I can’t easily emulate.

The most important things you can do to get your score up with Webflow sites is optimize your images, if you use Google fonts then download the fonts, upload them to Webflow and ditch the webfont loader.

I tried this today before your post and it does clear an issue or two but it actually took a lot longer to load a woff file from webflow so I went back to google fonts. So might be worth a revisit?