> Maybe it's just their own connection that sucks?
Your Core Web Vitals report in Search Console is based on Chrome User Experience Report data. Meaning that this is data from your real users, not Google running simulated tests of your pages on their own servers. I.e. when someone loads your page from Chrome, Chrome reports back how long it actually took the page to load for that user (it doesn't happen with all users, they have to meet various opt-in criteria [1]). So, if you see that 50% of pages are served too slowly on computers, it means that 50% of your real users actually experienced slow page loads (as measured by the Web Vitals metrics). Perhaps your static site isn't as efficient as you think, or your server is slow, or the devices/connection of your users is much worse than you assumed. That's the power of this data; it shows you that in the real-world the experience isn't as great as you're assuming and encourages you to investigate further.
(For the record) The landing page of the Core Web Vitals report does indicate where the data is coming from. Next to "Source: Chrome UX report" you see a question mark. If you hover over that question mark then click the "Learn more" link it takes you to this page: https://support.google.com/webmasters/answer/9205520?ref_top...
Disclosure: Googler working on https://web.dev. I'm not on the Web Vitals team but interact with them.
Your Core Web Vitals report in Search Console is based on Chrome User Experience Report data. Meaning that this is data from your real users, not Google running simulated tests of your pages on their own servers. I.e. when someone loads your page from Chrome, Chrome reports back how long it actually took the page to load for that user (it doesn't happen with all users, they have to meet various opt-in criteria [1]). So, if you see that 50% of pages are served too slowly on computers, it means that 50% of your real users actually experienced slow page loads (as measured by the Web Vitals metrics). Perhaps your static site isn't as efficient as you think, or your server is slow, or the devices/connection of your users is much worse than you assumed. That's the power of this data; it shows you that in the real-world the experience isn't as great as you're assuming and encourages you to investigate further.
(For the record) The landing page of the Core Web Vitals report does indicate where the data is coming from. Next to "Source: Chrome UX report" you see a question mark. If you hover over that question mark then click the "Learn more" link it takes you to this page: https://support.google.com/webmasters/answer/9205520?ref_top...
Disclosure: Googler working on https://web.dev. I'm not on the Web Vitals team but interact with them.
[1] https://developers.google.com/web/tools/chrome-user-experien...