Efficiency is only on powers leveled 25-60 and performance applies to 60-100+.
"efficiency" gives you more power at lower levels.
"perfomance" gives you more power at high levels.
So (I'm making up numbers here) if you where to max efficiency you might get 35 engine power with a 25% setting but only 102 if maxed out at 100%. If you where to max performance you'd get 27 at 25% and 110 at a 100% setting.
Hopefully this would multiply for each BO u have with efficiency. You don't need to train 1 point into each skill to get the bonus with the other space traits, and I'm assuming u have to get to commander rank to get efficieny to work - possibly the same for the BO's
I did pick the Borg BO, and preordered on the 16th of Jan, but Amazon dont tell me they've run out till yesterday when it is too late to get any other preorder bonus... :S
You can get +52 to each efficiency stat through skills, i never understood why people assume it meant +5 power, if that was the case the lowest power setting anyone would ever have would be 82, thats would remove the point of having power levels