What must be increased significantly to achieve a fast transit time under five months?

Initial velocity change (\Delta V)

Achieving a shorter flight time, sometimes referred to as a fast transit, requires injecting the spacecraft onto a trajectory that is inherently faster than the standard, fuel-conservative Hohmann arc. This accelerated path necessitates a much larger initial velocity change upon departure from Earth's influence, which is quantified as a higher Delta-V ($\\Delta V$). This increased energy demand translates directly into burning significantly more fuel during the launch phase to attain the necessary escape velocity for that quicker trajectory.