Orichalcum Chainsaw

Wood is not the bottleneck by hardmode, so the reason to build this is bulk speed: jungle clearing, cactus farms, and the hundreds of trunks a tree farm eats over a run. Holding the cut rather than swinging saves more real time than it looks like on paper once you are working through a whole biome.

Standing close enough to cut also means standing close enough to be hit, and the hardmode surface is not a friendly place to be rooted in one spot. Near anything hostile the Orichalcum Waraxe keeps you a step back. The Mythril Chainsaw is the same tool on the other ore, so your world decides which one you get.