I don't think John Deere is known for fuel efficiancy. I don't know if a 5093E compares to the ones you are looking at but I can burn through $150 of fuel in a day easily. A neighbour with a similar sized massey can do the same work for 5-10% less fuel. I do find the Deere a nicer tractor to drive but it is very thirsty.
Do you have a hole in your gas tank? I'm serious in asking this. My 5410 (85 HP) at normal operating RPM (not PTO), will burn less than a gallon per hour. Even at the high end of a gallon per hour (for math simplicity reasons), and diesel at ~$4.00 locally, it would take me over 37.5 hours of straight running.
Nobody runs at RPM speed 100% of the time - most of what I do is under 1600 RPM's - which is half of RPM speed for me. All brands will burn relatively the same amount of fuel.