Nitro is actually a very poor fuel because it's only got half the heat value of methanol, pound for pound (gram for gram, whatever). For nitro to give the same power as methanol you'd have to burn twice the mass of nitro. And this is exactly what happens.

All fuels have a certain air/fuel ratio where they burn best to give maximum power. For petrol this is about 12.5:1 (which is slightly richer than the ideal or stoichiometric ratio) and means that you need 12.5 pounds/grams/whatever units of air to burn 1 pound/gram/etc od petrol. This is the usual way of giving the ratio but for the moment we'll switch the ratio around to fuel/air because it's probably easier to see the differences. So the fuel/air ratio for petrol becomes .08:1 which means .08 pounds of petrol burns in 1 pound of air.

For methanol to burn and give maximum power the ratio is .18:1 so you can see that you need a little more than twice as much methanol than you would for petrol using the same amount of air.

Now nitro. This one is strange because it gives maximum power over a huge range of mixtures. The minimum ratio is .4:1 or just over twice as much as methanol. This is where nitro can just barely be better than methanol because it's only half as good a fuel as far as heat value goes. But nitro still works extremely well at a ratio of 2:1 which is near enough 10 times richer than methanol at .18:1. Is it any wonder that needling with nitro seems so much easier than with straight methanol? But the fuel consumption can be huge compared to running zero nitro fuel.

Naturally, when you have a mix of nitro and methanol then the ratio falls somewhere between the two extremes of .18 and 2 but the fact remains that extra power comes from increased fuel consumption. So you pay more for fuel that gets used up faster, kind of a double whammy on the hip pocket .