I am not sure if this has been done before, but while I was sitting in college bored out of my mind, I was thinking about what I saw in some videos on Youtube.
They were talking about how people inject cows and chickens with growth hormones to make them bigger and beefier etc.
The Predators being the advanced species they are, probably injected something into the Facehuggers or eggs, or they could have genetically modified these Aliens because they own them, they had a chained queen she could either have been captured wild or was a captive bred queen that grew in Predator captivity.
Wild Aliens will take hours to grow, while Predator-bred Aliens will grow faster so that Youngbloods can go straight to the hunt.
Also in AVP-R the Aliens were quite dumb, this could be like dogs and wolves, obviously wolves are smarter because dogs have arrested development, which means that wolves will mature while dogs even when adults will continue to act like teenage wolves.
The Aliens in the Alien movies where much smarter and more menacing than the ones in avp (except for Grid who was a lucky one)