The Bubblegum Extra and OG Kush seems to have grown out of their mutations a LITTLE although they are still considerably slower than the rest. They sprouted a couple of days after the Original Orange Bud and Cocopopo but yeah I would still say their growth rate is much slower.
Being a first year grower and the eagerness to learn everything about growing is making me keep the weaklings which, for me, creates more opportunities to work on that knowledge.