If you are using Steam, please follow this short guide to create separate installations of the game. Practice for this category should always be done with a separate installation of the game using the Debug Menu Mod with savestates. To downpatch with Steam, use this guide made by Verulean.
It is the fastest primarily because of the Lever Skip, which allows us to skip a portion of the spire before Watcher Knights. The recommended patch to run is Patch 1.2.2.1.