Peak Files
A peak file (extension .gpk) is automatically created by WaveLab Pro each time an audio file is modified or opened in WaveLab Pro for the first time. The peak file contains information about the waveform and determines how it is drawn in the wave window or the montage window.
Peak files speed up the time it takes to draw the corresponding waveform. By default, the peak file is saved in the same location as the audio file.