Cycling in the Alps - Alpe d'Huez - Properly

I climbed Alpe d'Huez on the first day of our holiday but turned right at round corner 4 so whilst I got to the top I did not follow the classic route ("Itiniere De Tour"). So I did it again and made the effort to get to the proper TdF finish rather than the top of the climb in the village.

Despite having climbed it once before and therefore knowing the route better I was slower everywhere that the first time I had climbed it - how could that be?

Here's the link: https://www.strava.com/activities/336010344

Here's me (after the 2nd attempt) at the top of Alpe d'Huez: