The reason they feel slower is that the higher volume tires transmit vibration to your body at a different frequency. You might be surprised that they may not be slower at all.
I've been riding my touring bike lately (something like 1000 miles in the last 3 months), and I'm setting new PRs on Strava nearly every day, PRs that were set with my road bike. Maybe I'm getting stronger, too, but my touring bike weighs ~30 pounds!
Don't assume it's slower just because it "feels" slower.