Well, this is weird. I'm trying to tweak how GPP is handled. Make it so any GPP born increases everyone else's GPP threshold slightly, yet make it so the threshold decreases slightly each turn. While doing some testing trying to reduce the modifier by 10%, it was being reduced by 15% instead (I guess speed/worldsize related?). Additionally, when I spawned a great person, the GPP threshold increases up to what it would have been normally! That is, rather than incrementing it by the the +100 I had intended, it shoots up to 1000 (after a few have already been born).
The function called when a great person is born is supposed to add the value from the globaldefines XML * (number of great people)/10 + 1 - Or, I suppose, every 10 people causes the threshold increase to double. However, instead of adding it seems to be setting the value.
Edit: Found the problem. Turns out GPP was being calculated different than I had thought: the normal increase is applied, and then the team increase is applied as well. When added on top of a doubling of the base rate and doubling of everything else, the progression was, before cost reduction, 200, 600, 1000, etc. Now it's 200, 400, 600, etc, but with the diminishing factor in, it should settle in at a comfortable rate. As a note, I did leave in the extra cost bump, so after every multiple of 10 great people, it goes up even more.