I mention as often as possible that the rate at which a snake grows can and also does not always mean there's anything wrong. However if you had hoped to raise a pair of snakes to maturity as soon as possible then there in most cases is a way to influence that to happen.
If your snake spends most of its time in the hottest area of the cage then maybe try to offer the female twice as much food for a few feedings and see how she reacts. If it seems to make a difference then that may be all that is needed. Be wary of cranking the heat in any males cages, I think it can have adverse affects on his reproductive future. However if they spend a lot of time on the colder side maybe the cage is too warm and is stressing them out?
I have a few Cal Kings here, had not kept them in years but I got a pair on breeding loan and scored a nice huge female too. I traded a pair of Brooksi for a yearling female Cal King too and she is quite small, as with Brooksi I often see them at 30 inches in their first year. I do not have much experience with Cal Kings but I do think they have a tendency to grow slower than other Kings...can't really say for sure.
Try different things. Crank the heat in one cage and lower it in the other. Either feed a few rodents per feeding every 5-7 days or maybe just one or two rodents every 2-3 days. Just make sure that the snake is pooping a lot, if it is just getting fat then something needs to be diffferent.
I said in the info from the article I posted above and what I have seen in my collection, it seems sometimes if a snake did not grow to its maximum potential in the first year of life it may not ever pick up speed as far as its rate of growth. It may continually grow at what you feel is a slow rate. That's just the way it goes. It is why I say a snake willing to eat like a pig and grows like a weed is a winner in my book, but it does not make snakes that do not grow as fast losers....they could be perfectly healthy but simply don't grow so quickly.
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