To add to Salamandre's post, the despotism tile penalty also applies to shields and gold, and operates to reduce ourput rather than cap it. While in despotism, any tile that produces 3 or more of an item, will produce one less than it would in any other government. So, for example, a roaded plains tile with a cattle will normally produce 1f, 1s, 1g from the plains and 2f, 1s, 0g from the cattle for a combined 3f, 2s, 1g -- but the despotism tile penalty means you only get 2f from the tile. If mined, it would normally produce 3f, 3s, 1g but the despotism tile penalty reduces both food and shields, menaing you'll only see 2f, 2s, 1g. If the tile were instead irrigated, it would normally produce 4f, 2s, 1g -- the despotism tile penalty would take away one food, leaving 3f, 2s, 1g.