And stability is designed in, to suit the boat/ship's purpose. A navy ship will have lots of righting arm, and be "stiff", meaning she snaps back quickly from a roll to level. Why? So the gun deck will be level most of the time, for firing. This is harder physically on the crew than a slower rolling period.
A cargo ship will have shorter GM and a slower rolling period, since a slower roll is gentler on the cargo, lashings, and crew. It's 'tender', but meant to be that way.