i need a setting slower than very slow.
PacingDefs.xml, you are welcome.
It won't do you much good though, because the effects are additive to what citizens and improvements do... a research world with 15 research; +150% from improvements and citizens, goes from 37.5 research to 30 research if you set research to very slow.
I double-checked. The pacing stat does in fact apply to bonuses given by citizens and xenophobic. But it is still additive with the bonuses from improvements.
I tried to mod to add a different kind of bonus before, but didn't succeed.