PSA: (Last I played) Huge+ galaxies start to have performance issues with genetic engineering in the mid-late game. Different subspecies are treated as a different race, which each require their own computations from the AI for things like migration, happiness, reproduction, and so on. The game can become unplayable, depending on your hardware.
There are mods that can limit the computer making 5 million sub-races and allow you to clean them up manually, but I don't know if you need to start the game with them enabled, to take full advantage of the performance boost.