I haven't done the new space age timed run achievements yet. I still consider the timed runs to be 15hrs and 8hr... lol.

Much of the same rules apply im guessing: Adjust resource settings to be higher density, pre-blueprint a lot of stuff, bum-rush construction robots as fast as humanly possible. Build wide with low teir belts/machines, don't bother with optimizing, modulizing, or investing your limited resources into higher level belts or machines.
Also, your character crafting queue should NEVER be idle. You should always be making some kind of construction material, or if you don't need that, then science packs. It helps.