Faired can cruise at 60km/h on the flat at similar effort to 25km/h on a road bike. Marginally slower on steep uphill.

Unfaired won't have you going much faster, maybe +5km/h on the flat and -3km/h on the uphill.

At high speed on flat ground aerodynamics matters significantly more than weight, so velomobiles tend to be a lot faster.

Uphill is a different story.

I hit 90 km/h on my recumbent as a fat bloke loaded up for touring. It was on a downhill though :).