One of the most requested features for Gig Performer was a built-in MIDI file player and Gig Performer 4 now includes a MIDI File Player plugin:
The MIDI File Player plugin can load up to 128 different songs. For each song you can easily select which tracks to play and optionally map them to specific channels. A looping feature is also supported, where you can specify both a start and stop position.
Refer to the MIDI File Player chapter for more information.