The test script attached to this KB article introduces the function:
Dump page load time:
NavPerformance();
You can call it at any time after a web action is performed (Navigator.Open or SeS(‘…’).DoClick()) and you want to check the last page loading time or see information about the loaded resources.
There are a couple more uses of this function.
Dump page load time and resources:
NavPerformance(true);
By default this function returns the page load time in milliseconds as a number. So you can use it later for additional validations. A extra benefit of this function is that information about the timings is also written into the report.
var tm = NavPerformance();
Tester.Assert("Navigation took less than a second", tm < 1000);
To return page load and write nothing to the report:
var tm = NavPerformance(false, true);
Implementation of this function is in the .user.js file of the attached test. If you have complex test set you may put it into a common .js file for all your tests.