Or to put it another way, people waste 10% of their time on the web waiting for slow bloated garbage to load (or more when you take into account pages that do more loading when you touch them afterwards)
This just shows that they don't even understand what they are measuring.
With their engineering leader [1] arguing that 2.4s to display text and images is fast, no wonder they present "people still spend time on websites after they have spent an eternity loading" as a surprising find.
Less obvious than you think. How long do you spend on the HN front page? When you open say Gitlab how often do you stay there and not immediately click to something else?