What does performance speed refers to? Aircraft performance in general
Read the POH - it will show the conditions the speed was measured under.   


  Cruise, 75% Power at 8500 Feet. . . . . . . . . . . . . . . . . . 122 KNOTS
  
  NOTE
  
  *Speed performance is shown for an airplane equipped with
  speed fairings which increase the speeds by
  approximately 2 knots. There is a corresponding difference
  in range, while all other performance figures are
  unchanged when speed fairings are installed.
  
  The above performance figures are based on airplane weights at 2450
  pounds, standard atmospheric conditions, level, hard-surfaced dry
  runways and no wind. They are calculated values derived from flight
  tests conducted by Cessna Aircraft Company under carefully
  documented conditions and will vary with individual airplanes and
  numerous factors affecting flight performance.


(http://www.airilm.com/wp-content/uploads/172R-POH.pdf)