I don't think you can make it faster or easier to pedal. It's a cruiser bike - it's designed to be comfortable for slow speeds and mostly short distances.

The big padded saddle is problematic for long distances because it puts pressure at points where you don't really want it. You can get some improvement by changing that out but still, sitting very upright transmits all of the shocks straight up your back. The best bet may be a suspension saddle with less padding.