The change

effectively halves the number of pops in the game, but does so in a way that feels bad because it leaves worlds empty and artificially restricts growth.

You know what else would halve the number of pops?

*Halving the number of pops.* Districts do 1 housing/1 job instead of 2, buildings require 1 pop instead of 2, cities house 4 instead of 7, etc. Double the growth time, upkeep, and output of a single pop - you now have half the number of pops but all the worlds are filling up and you've got the same economy as 2.8 with half the CPU load from pop calculations.