Besides oscars (which I know grow very quick, like they're on steroids) and flowerhorns (which from personal experience I know grow relatively quick), what other large cichlids grow pretty quick, given the appropriate size tank and excellent water parameters, excellent diet etc. Just for perspective, I know frontosas are a slow growing large cichlid and I can akin them to a giant dog breed, which can take up to 2 years or more to reach max size.