Turbo Boost is not what you think it is. Turbo Boost allows your CPU to temporarily increase the frequency when load demands it.
Two caveats, the first is that its not instantaneous, it generally increases frequency by set amounts as it needs it, and will eventually reach its peek boost frequency. This happens fairly quickly, but if you wanted it for those few hitches every now and then, chances are the hitches have already occurred by the time the boost kicks in by any meaningful degree.
The second is that the CPU cannot maintain this peek performance for very long. The idea is to provide an extra boost to quickly finish a demanding task. So you are not going to be able to get a nice consistent boost in performance in a demanding game.
Turbo Boost is not something thats controlled by software (although your CPU vendor can provide software to tweak its settings), it kicks in automatically when the load demands it. Its not something that Citra needs to enable.