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.