I started with a Dixon 4228 42" in '95 when I had 1/2 ac to mow. (~$2k) It took ~ 3hrs to mow 1 1/2 ac when I moved here in '01, so in '06 I bought a CC RZT50". (~$3k) That cut mowing time to ~2 1/2 hrs.
In '15 I bought a Husky MZ-61. This one has a B&S 28hp engine, HG 3100 drives, and a pro (welded) deck. It's like a stripped-down pro model with a homeowner motor (love it) and no ROPS. IMO it's worth every penny of the near $5k I sprung for it. I'm mowing 2 ac now and get done in < 2hrs. Only thing I've done except oil changes, blades (Oregon 95-086), and one belt is to add flat-free front tires.
My personal bugaboo is a disdain for Kohler power. (keep fixing on OPs') Well, that & MMMs.
/ Replace with new tractor or add a zero turn mower
I think it depends on the size of what you are cutting and the layout. I can cut what I have pretty fast with my tractor but it is 4 acres of mostly grass on a level ground. The zero turn is faster. BUT, my tractor has AC and a nice stereo, so I'd go with my tractor even if it took twice as long in the 95 degree heat with 80% humidity like we get on the coast in the deep south. Don't even get dirty. LOVE mowing with the cab setup. When I mow, it's like a scenic drive in the country with some good tunes and cold air! Rain or shine as well. Just turn the wipers on and enjoy the ride.
