That would require me to successfully work BF's search tool a second time - it was hard enough the first time.
But to be helpful, this is what I found from previous BF threads on the subject:
A fairing allows a recumbent bicycle to cruise much faster with far less effort, a sustained 25-30 mph becomes quite easy. It will dramatically improve acceleration and hill climbing, especially on steeper grades. Subjectively the difference is reported to be like an extra 100-200 watts, increasing with speed. On group rides, riders on faired recumbents easily outpace even young, strong DF riders, as attractive lady DF riders, quivering with longing, gaze admiringly at the recumbent riders' rippling leg muscles and sleek Aerobellies.
Wait....
A fairing almost never helps on hill climbing, at least not steep hills.
On flats and down hills, at speed, air resistance is the biggest thing slowing you down. Once you are climbing (steep) hills, it's gravity and the (small at low speeds) gain due to less wind resistance is going to be offset by the added weight.
And, of course, in this case, size does matter (the size of the fairing, that is)...
The part about the admiring gazes, that's all true.