Hampton Bay Altura runs slow, even on high speed.
I suspect the motor is running perfect, just under powered.
I cannot find a motor spec anywhere.
Can anyone confirm my suspicion?

I suspect you are correct. No residential fan should be larger than 52", 56" at the most, without running slow.

I checked an Altura ceiling fan (cannot remember the diameter). On LO: 35 RPM, on MED: 65 RPM on HI: also 65 RPM. I cannot get the fan run faster than 65 RPM. No clue why.