Energy consumption in extruders depends on the energy required by the drive motor and the energy required for heating and cooling of the extruder barrel. This work investigated the total energy consumption of high speed twin and quad extruders using a three phase power meter. Both extruders had 15-mm-diameter screws with length-to-diameter ratios of 45:1, and the same 22-kW motors, but the different number of screws changed the clearance between the screws. For each extruder, energy consumption was evaluated as a function of screw speed, feed rate, polyethylene type and molecular weight, and content of calcium carbonate filler. On-line measurements of viscosity with slit die were conducted to examine the performance of extruder design and the effect of that energy on viscous dissipation. The resultant extrudate was characterized for rheological properties and discussed with respect to material structure and viscosity as well as extruder design.