I had it in my mind that I wanted to try and shave time off my commute so I converted my LHT to lightweight 26" wheels, 25x1.75 Travel Contacts, compact double, 11-28 rear cassette, and Specialized Romin seat and it felt pretty quick. Steering was sluggish but acceleration and speed were great. It lasted all of about 2 days. With all my commuting gear, it really didn't make that big of a difference in time and I missed the comfort on bad roads. Quickly went back to the B17, Big Apples, and original gearing.
Similarly, I'm commuting on a disc trucker after having done the same on a lightweight trek race bike. I love the trucker. Yes, it feels heavy and slow. But I have a 1.5 hour commute and find I've only lost a few minutes maybe by riding the trucker.
But I love the solid contact and good handling I feel on the trucker. And I'm not just barely getting by on cargo capacity. I can run errands on the way home without worry that I won't be able to carry a quart of apple juice. And the backpack is gone along with having my back drenched in sweat.
A few minutes of my ride is fine to sacrifice. After all, sometimes I artificially extend it anyway because it feels good. The quality of the ride I'm finding to be more important than the speed alone. The speed is not as different as my initial perceptions would indicate.