The genetic storage building (drawing a blank on it's real name), doesn't cost much at all, but takes a lot of turns. That's probably to simulate the procurement of the genetic material across your empire.
Actually, it's for game balance
The whole bioterror/genome bank mechanics need reworking at some point (bioterror sucks because the genome bank stops it completely). If I go to the effort of setting up a bioterror projection base and then you can expedite cutting it off completely then I've wasted all my work. Turns to build is one of the balance mechanics in the game and in some cases it's a fairly important feature.
Drydocks, for example, are going to have their costs increased at some point (they're far too cheap but the AI overbuilds them and until the AI production glitches are solved it's a low priority), but the ability to, for example, capture/colonise a planet in the heart of your opponents area then expedite the shipyard and drydock to be able to repair all your fleet really quickly would be speed up the steamroller effect that we're trying to slow down.
Rule of thumb: pretty much everything in the game is restricted for balance, then a justification is written up, it's not a simulation, we don't do stuff for realism, we justify things to keep suspension of disbelief going.
I am always happy to consider rebalancing things and change build times (I'm working on a couple right now), but I'm loath to have a catch all time reduction ability (we recently took one out that had been annoying me for ages) because the build times are set for a reason.