Several metrics are collected from the DOM (Document Object Model) of the users browser when the window.onload event fires. This is after the page has already loaded so it will not slow down the speed of the page load. A few bytes of information is sent asynchronously back to via an HTTP(S) GET request to collector.webtuna.com where the data is processed and stored securely.
About the Author
PowerBI Content Pack – Getting Started 1st September 2016
How is WebTuna different to Google Analytics 14th July 2016
Where can I find my REST API key and how do I use it? 9th March 2015