The Performance Shifter proc can be slotted into auto powers (Stamina, Quick Recovery, Superior Conditioning, Physical Perfection) for a consistent check every 10 seconds, but does not in and of itself boost your Endurance recovery. It has a 20% chance for 10 Endurance (regardless of your max Endurance) which triggers every 10 seconds, which averages out to 0.2 eps, but is neither guaranteed nor suitable for combat considerations.
Totals in Mids shows Endurance replenished over time due to Recovery, but this nebulous "you'll average out to some 0.2 endurance per second with this proc" measurement doesn't have anywhere to go.
And since it should be said, Performance Shifter's proc in auto powers should not be considered the same thing as Recovery, no matter how you slice it. It's an average, but in practice you'll see sometimes more, sometimes less over any given time frame.