That's odd. That seems unusually high for a Caldera Cone.

I use a Caldera Cone with a 850ml MSR Titan kettle with a tight lid. I can easily boil 16 fl oz of water with 18ml of green denatured alcohol or 24ml of HEET. Proportionally, it should only take about 45ml - 60ml to boil 40 fl oz of water, depending on what kind of fuel you're using. Your fuel usage sounds a little high.

What kind of fuel are you using? Do you have any photos of your set up in use?

You're boiling 5 cups at a time (1.25 qt) it sounds like. That is a bit more than the average alcohol stove user. Usually, when I boil that much at once I take a stove that uses a petroleum based fuel.

HJ