The total page rendering time (not php script execution time, but the time at which the entire page is rendered from the user's perspective - all images loaded, ads served etc)
The URL of the page
The browser used to access the page
The country the page was accessed from
The script should then store the information in a database via an AJAX call after it's been collected.
It sounds like a tall order, but it will help me get a picture of how fast or slow my site feels depending on where you live (e.g. how far you are from the server), what browser you're using, and which pages are the slowest to render (keep in mind this is not script execution time or query time, but literally the time at which the page starts to render, to when it finishes rendering).
Is that possible?