There used to be a suicidal difficulty level in the game, which marigolden has taunted about a year ago. This level has been since removed/renamed a few updates back.
However, with the nerfing of colony capital (a change I like very much), game pacing (very slow) + god like difficulty level + Iconian is the real challenge.
Here is what you get after colonizing a planet with 2.5 pop. 42 turns to build the first factory.

Colonizing with 0.5 pop? 97 turns to build the first factory.

AI does not suffer as much, 7 turns for Terran to build a factory with 2.8 pop

And Krynn is even better with their 50% pop boost during colonization - 4 turns

My thought: maybe game pacing could be a separate multiplier, as oppose to a linear one that can be cancelled by factories, or faction traits.