For the most part, trees grow slow.
And sorry to the young lady suggesting she gets multiple cords from one tree, maybe if it was a thousand year old redwood.
Here is a site that talks of tree to cord measurement:
From the research I just saw on Google, a pine tree of 25-30 years is harvestable.
The problem with "fast burning wood" is most wood stove users don't want it. They prefer a denser wood, like oak. Oak trees grow slow in the woods, about the same speed as pines in your backyard. That surprised me, I assumed most oak trees were over a hundred years old.
But I may be confused on whether you are for burning trees for heat, or against. If you follow Paul Wheaton and his Rocket Mass Heater friends, they're suggested uses of burning wood is usually scrap lawn debris, a cord or two per season.
And Ernie Wisener of the Erica and Ernie RMH duo, is experimenting with rocket mass heaters that burn hot enough to use plastic bottles for fuel, without emissions. It's been awhile since I studied his findings, but that sure seems like a great work.
I don't know if I ever mentioned it here on the permies forums, but I was thinking if a inventive sort might use the same, or similar process that is used in the creation of pressure treated wood, but for making a soft wood like pine, a dense wood like oak. Then make it affordable to homeowners, coupled with the efficiency of Rocket Mass Heaters, you would have a great sustainable product.