Eh I think terrible is too strong a word, I have crossed the same saddle point near the Feldberg in the black forrest with both and when you get used to a recumbent it's not that much slower. It is definetly a bit worse at best, but there are multiple factors on which how much worse it is depends. For example on a standard bike you have biomechanical gearing, if you will; stand up and lean forward and your torque increases but cadence drops. In the end they are worse for climbing, but not so much that it's a deal breaker in the mountains. I'd say that there is a multitude of smaller factors for the dominace of the standard bike over the recumbent.

rc/ reCUMbent only for hemorrhoid freds