anyone deal with slow growers?

Well.. They say slow growing female generally produces bigger clutches

I have a female that was returned to me as a hatchling after being neglected by an owner who lost his housing. She's a 2009, but she's smaller than some of my 2010s. She's an off and on feeder.

Also, I think the bit about 'slow-growing' females is unlikely (to say the least). Bigger females usually lay larger clutches. Since they do most of their growing in the first 4 years of their life, you can do the math on that one. I suspect size, growth rate, and clutch sizes are all related to genetics, all else being equal, and there's no reason not to feed a young ball python up well. I would be concerned that if you don't maximize their growth in the first 3 years, you may miss the window to having a truly large snake. They continue to grow over the rest of their life--but only extremely slowly.

I would look into de-worming your snake or at least having a fecal sample run. I agree with Simple Man, my picky Sept.2010 snake is nearly 500g. I would say on average she eats 1:3 times that I attempt to feed. I try every 5 days 10-15% of body weight for prey size. Sounds really strange to me that a snake that eats regularly would not grow.

What size prey are you offering? It should scale up as the snake grows. My 2010s are eating small rats now. (I do have one mouser, she's taking jumbo mice).

If you're offering prey as big around as the widest part of the snake's body, and they are eating them every week...then I agree, you should take a fecal sample in for a parasite check. Ball pythons that eat well usually grow quite fast.

People often underestimate how big a prey item a ball python can eat, though. My brand new hatchlings are already on small mice at 2 months old (big fuzzy rats would be equivalent).

I have a few slow growers. I have an '06 female that just hit 1000g. She was a problem feeder though. I have now figured out how to get her to eat solidly every week. I have a '07 pastel male that is only around 600g. He doesn't eat every week though.