This comment (from the code in Reply #17) is irrelevant. As far as the Arduino is concerned the interval between steps is entirely unrelated to the step angle. The Arduino has no knowledge of the step angle.
delayMicroseconds(26000); //7.5 degrees/step
That interval is equivalent to about 38 steps per second if my maths is correct.
If you are using the same program with the Nema 23 motor and using microsteps I would expect it to be moving much more slowly.
The best way to check for steps per revolution is to get the motor to move that expected number of steps and see if the flag on the motor shaft gets to the same place each time.
...R