How to cut a polyester ceiling insulation batt

Stainless steel knife cutting an R2.0 ceiling insulation batt. Stand on the pine so as to compress the batt. Chipboard under the batt to protect the floor. Australian video. Smaller cheap blades make the task just about impossible. Electric bread knives do work but are very slow. Two recommendations have been received but not tried; sheep blade shears and using a longer curved blade (with the blade on the outside of the curve). 1 x blade (product: Trogan Heavy Duty Stainless Steel Hacking Knife), 1 x marker pen, 1 x chipboard (to protect floor), 2 x pine 4"x1".