Are recumbents slower?
The speed you go will depend on the weight and style of bike you ride (on average, recumbents tend to be heavier), your conditioning, and the course being ridden (hilly or flat). In normal riding conditions recumbents will be a little slower than an upright bicycle even in the best of circumstances.
Recumbents, with a fairing, hold the human powered land speed record for two wheel bicycles. Unfortunately, in 1934 the international bicycle racing organization (UCI) banned recumbents from competition due to ‘unfair aerodynamic advantage’. If not for this happenstance recumbents would probably be much more popular today, regardless of any speed differentials.
What about hills?
Climbing hills can be the Achilles tendon for recumbents. Recumbents are generally slower on hills because of the additional weight of the bike and the rider not being able to stand up and use body weight to add power. Typically you just have to gear down and pedal when going up a hill. That is not to say that a well conditioned rider on an expensive lightweight recumbent can’t keep its own with upright bicycles.
Going down hill is where a recumbent shines! They are more aerodynamic and can attain higher speeds.
All things being equal, a recumbent can hold its own on most hills.