"Feels slow" doesn't always mean slow (although sometimes it does). Have you compared your times to ride a few routes with 23s and with your new bike?
The high-frequency road shock that buzzes your high-pressure tires, and you can feel in your hands and saddle, is easy to confuse with speed. Wider tires soak up some of that buzz, so you don't feel it, but it doesn't mean you're going slower.
And since you're touring, if it ends up you are riding slower, stop and take a picture.