Gathering boosts come in two types: one that increases the amount of harvests you get from a node, and one that increases the likelihood of rare/extra components from harvesting.
While each class has options that will make running the route more efficient, three in particular stand out: Daredevil Thief, Druid Ranger, and Scrapper Engineer (build suggested by Midge). All of these builds can be adapted for non-Heart of Thorns characters, but that is outside the scope of this guide.
There are a few things to consider when it comes to building for a resource run: Movement Speed, which affects how quickly your character runs; Movement Skills, which move your character quickly from place to place; Quickness, which affects the harvesting animations, which means you will gather faster; and Combat, which determines how quickly you can kill or lose aggro on monsters in order to move on. If there are portions of a build that are not specified, they are nonessential and are up to the player's preference.
How to use: Remove hindering conditions with Vine Surge, heal, elite, or Quickening Zephyr in order to maintain 33% movement speed. Use Ancestral Grace when off cooldown. Keep pet set to passive, because if a mob attacks it and not you, you stay out of combat until your pet attacks it. Use the f1 command to have your pet kill things while you harvest.
How to use: Dodge as often as possible to maintain Swiftness and to move quickly. When out of endurance, use your heal skill to regain some so that you can dodge again. I rarely find a need for Infiltrator's Arrow, but it is good for moving quickly up ledges.
How to use: Pull out the Flamethrower, turn Elixir U on as your autoattack (ctrl + right click) and get ready for some perma-quickness while gathering! Pop Elixir B for the occasional speed boost. Please note that if you use an Item Booster with this build, it will unequip your Flamethrower after every harvest due to a bug.