well if you don't care about human rights you can always nerve gas them
and bases you have recently captured probably have reduced pop (less use of resources) more drones, and are surrounded by the AI's stupid terraforming like farming arid squares. and if you're the pirates, you get +1 mins from ocean squares, so send some trawlers in, change the support to the captured base, and send them off to harvest mins from your platforms (maybe even rush a trunkline). so in your transport you probably have some marines a rover maybe, add another garrison or 2 so you can defend the base after u capture it.
and as for new land bases, they actually tend to be more productive (depending on location) with more energy from boreholes and what-not. a land base i have as the pirates is my most productive base. new bases you found later in the game usually take longer to get going anyway right?
hope that helps