I agree... It's probably like those 6hp 22" cut push mowers that don't have the grunt that the 3.5 hp mowers had when I was a kid.
Ian
I am thread drifting here, but here goes anyways. Also I will more than likely get kicked about the design aspects by some not looking into the physical performance.
Older lawn mowers used Straight Blades keeping the blades impact surface and drag surface to a minimum. This type of blade requires less horse power to cut through grass, but in turn does not mulch and may require raking and bagging the clippings if they bother you.
The new High Tech, High Lift Blade designs do help mulch and give a little more appealing finish cut, at a price of more fuel used per cut and more frequent cutting intervals.
My High Lift finish mower blades have a height of 1 inch, I made a set of Straight Blades with a height of 1/4 inch. The performance difference between the two, using my little 16HP CUT is HUGE. I run at lower RPM's, and a higher gear with practically no bogging down when hitting thick grass. With the High Lift Blades I would need to down shift and increase RPM's, which helped, but at times the deck would load up and bog down anyway.
The results are, I have less seat time cutting and I am burning less diesel fuel. With the 10+ acres I keep cut, it has been worth every bit of research I did before doing it. The benefits out weigh any argument of High Lift Blades for my use.
Sorry for the thread drift, I do think the Original Poster had his question answered already.