My last game I had 80,000 threat just from DS ships alone. Wading through that is like walking through a tar pit
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There are plenty of things you can turn on to impede your progress. DS, Hybrids, Golems, Spirecraft, and the AI you choose to play against.
I've taken to cranking up Enclaves and Wardens as well.
Have a need for AI controlled champs wandering the galaxy? There is an AI for that.
Play around with the options we have and see if there still isn't anything that will give you the challenge you want.