No, they do it in a fair way, I believe if you read the page it will tell you how they fairly measure performance between the forges.
Edit: see "Expand for details on methodology" right at the top of the page.
Edit: see "Expand for details on methodology" right at the top of the page.
Anyway, it suffice to use gitlab, github, bitbucket and sourcehub for a few seconds to notice the slowness of the three first sites compared to the last one.
We didn't really need the numbers to be convinced but I hope they will produce some pressure to be faster.