I've noticed something whenever I settle "colonies" outside my home continent. The production levels on some of my cities are so low, it takes 100+ turns to produce a builder. It isn't the case with a few cities which are settled near rivers or who have a big housing capacity. From this I could guess that production is contingent with housing and proper water sources (oases don't seem to give the same value as rivers). I figured it's a matter of producing food for my cities. I had one city where every tile surrounding it was farmland. But it still didn't work, and it takes me around 50+ turns to build a Campus on that city. What am I doing wrong? Do you guys have any tips on how to max production in cities that are outside the home continent, besides policy cards?