How to run stepper motor at its maximum speed
As this link states:


  Stepper motors are normally used for positioning, and are not known
  for their speed.


However, the link is to an on line stepping motor speed calculator.

As for the size of the step, this is a function of the way the stepping motor is built.  Some controllers / stepping motor combinations can do half steps or micro steps.  Disable these feature for the fewest number of steps per revolution.

These are some of the basic concepts which deal with practical stepping motor applications.  As speed increases, other factors come into play.  For example, resonance and inductance.

In this paper resonance is discussed:


  If a rigidly mounted stepping motor is rigidly coupled to a
  frictionless load and then stepped at a frequency near the resonant
  frequency, energy will be pumped into the resonant system, and the
  result of this is that the motor will literally lose control.


The paper also discusses the effect of the stepper motor's coil inductance:


  An important consideration in designing high-speed stepping motor
  controllers is the effect of the inductance of the motor windings. ...
  The inductance of the motor winding determines the rise and fall time
  of the current through the windings. ...