When Does Google Consider Page Loaded?

I’m running a test in webpage test and the fully loaded time is about 120s because there’s a script that is calling the same file every second. I know that webpagetest considers a page fully loaded when no activity happens for a full two seconds.

However, when I run the same site through tools.pingdom.com, the page is considered loaded in about 3s.

How should I interpret this information when optimizing a site for a client?

Thanks in advance

The DOMContentLoaded event is fired when the document has been completely loaded and parsed, without waiting for stylesheets, images, and subframes to finish loading (the load event can be used to detect a fully-loaded page). A page can’t be manipulated safely until the document is “ready.”

I got that from here

Google seems to place as much or more emphasis on the User Experience as indicated by the time it takes for the website image to appear - the First Contentful Paint.

From Google’s Developer FAQs:
“First Contentful Paint (FCP) measures when a user sees a visual response from the page. Faster times are more likely to keep users engaged. DOM Content Loaded (DCL) measures when HTML document has been loaded and parsed. Faster times have been shown to correlate with lower bounce rates. We encourage you to look at a variety of metrics, including FCP and DCL to understand the performance of your page.”