Is a recumbent trike faster than a non-recumbent bicycle? I am seriously considering getting a recumbent trike, probably one in a tadpole configuration, and was weighting up how much time I would save during my commute when compared to my normal bike.

Currently, I ride Giant Cypress and my speed averages about 22kmh on my commute. My commute is about 16kms, one way, and is over a mixture of forest trails and asphalt bike paths. 

I am also thinking about using the recumbent bike over the winter months as well.
All other things being equal (which admittedly, they never are), a recumbent trike will be slower. It has more frontal area, more rolling resistance, and more weight. 

I don't have a recumbent bike, but I do have a conventional racing bike and a recumbent trike (a very low-slung tadpole, not a delta). On a frequently-ridden 37-mile loop, my average speed on my racing bike is about 15.5 mph, average on the trike is 14.3 mph. So at the speeds and distances you're riding, the net time difference won't be that great.

All that said, the trike is a lot of fun.