There is a bit more to factor than the theme itself, if they were on the same server with the same plugins installed the test would be a lot more relevant.
The test turned out to be incomplete, to put it mildly, I also think that the templates: Warehouse, Alysum and Panda, deserve attention.
Maybe on PrestaShop 8?
It's always a pleasure to see these kind of reports. For sure it s time taking but in the end it s worth understanding how the speed of a website works