You can do that in RealBand

Edit - MIDI - Length of MIDI Music



This command alters the length of the marked area of all selected tracks by the specified percentage. For example, 50% will shorten the length by half. You can use the Data Filter to determine which events are affected by this command.

This command supports floating point percentages. You can specify a length percentage as a floating-point number, such as 110.5%