You may be right the speed is dependent on GDP/development/pop of the planet concerned. I don't remember which ones had those 20s build times, wasn't watching that closely. It's also a lot later than the save you've got, things have moved on since (although i still haven't found the blighter's bases), However as i say I've never seen these hideouts built so quickly before and i can't see whats particularly different about my current game. The only thing that's different is these particular pirates. I think going 6-8 troops per colony, even if you could technically afford it, is too much. You could field two additional fleets for that over 30-odd colonies. I'd rather have the fleets.
Not sure it's supposed to be annoying, I suspect it's so that the pirates represent a significant threat that you can't easily counter without finding their production and support assets and taking them out. Which is fair enough in itself, except that the mechanism creates a really annoying and uninteresting mini-game of whack-a-mole.
Yeah, I've already taken three of their colonies and their capital
Thanks for the tip about democracy. Sounds like a good idea.