I'm new GalCiv games, i'm just starting my 4th game. after lossing the first two i think i'm getting the hang of it, but there are a few things i don't understand, one of which is just how production is calculated. I'll have two near identical planets with completely different production outputs, eg:

Nestor IV

1 Factory on a 300% production bonus tile
Planet bonuses: 10% prod, 15% econ
Population 0.45b
Approval: 100%
Social Production: 24 units

Russom III

1 Factory on a 300% production bonus tile
Planet bonuses: none
Population 2.52b
Approval: 100%
Social Production: 5 units

Poseidon II

1 Factory on a normal tile
Planet bonuses: 10% prod
Population 1.1b
Approval: 81%
Social Production: 10 units

All factories are lastest model availible to my civ. Sliders have remained at 50% social and 50% research since game start.

Why does Russom III produce hardly anything? It has 5x the population of Nestor IV but produces just 20% of the output. Does the a 10% planetry production bonus really make such a big difference (i.e. >400%). I've tried everything i can think to fix Russom III, what i'm i missing?

Thank you for any help.