I am really disappointed that Catalina didn't see fit to put a large enough thru hull to allow a quicker pump out.
The thru-hull is 1" because 1" is the size of the discharge port on the macerator pump, which means the discharge hose has to be 1" and so does the thru-hull. That's not the reason for slow pump out....if it were, everyone who has a macerator pump would have the same complaint. Low voltage to the pump is the most common reason for sluggish discharge from macerating toilets and pumps.
A worn out impeller is another reason. Every time an impeller pump starts, it runs dry for the couple of seconds it takes to prime...that wears a minuscule amount off the edges of the impeller vanes each time. And the "looser" the impeller is against the inside of the housing, the less efficient it becomes. So first check the voltage to the macerator pump...if it's getting a full 12v, replace the impeller.