How can i make my nile monitor grow faster

[RedTailedBoa]

Hi there, this is my first question on this forum which i was lucky to find because yahoo answers sucked at answering my questions.
Anyways i bought a baby nile monitor around 2 weeks ago which i was very lucky to find in stock at my local LLL Reptile after 2 years and he has been eating great, his cage is a custom made 10ft long 3ft wide and 2ft tall, he ate the first day i got him and still eats without any problems, he is skittish whatsoever but never bitten me before, i feed him a mixture of roaches and crickets around 6 every other day.
I'v seen people with 3-4ft one year nile monitors which surprised me, are there any possible ways to make him grow faster without "overfeeding"? Thanks!