This extreme machine from Canadian manufacturer Denis Cimaf swallows a tree in 15 seconds. As their website says-
DENIS CIMAF Inc. specializes in developing high-performance industrial brushcutter-mulchers, land clearing equipments for excavators, backhoes, skid steers, forestry tractors and graders. In applications such as land clearing, forest fire prevention, roadside maintenance or power, oil or gas line right-of-way preparation or maintenance, DENIS CIMAF forestry mulchers are recognized for their productivity and effectiveness.
Such machines are exactly what we need for a highly productive and unsustainable world. Yet, you can admire the machine in the video.