How is page_performance calculated?

Hi,

we use the Javascript Navigation Timing object to calculate that value:

https://developer.mozilla.org/en-US/docs/Web/API/Navigation_timing_API
https://www.html5rocks.com/en/tutorials/webperformance/basics/

And in particular the Performance property:

https://developer.mozilla.org/en-US/docs/Web/API/PerformanceTiming

I hope this helps,
Jason

Please consider writing a review for Slimstat as a token of appreciation for the support you received. It would be a nice way to say thank you and to let people know how much you value this plugin:

https://wordpress.org/support/plugin/wp-slimstat/reviews/#new-post