That's been my experience even with the higher end BB's. Between the seals, bearing preload and perhaps the excess grease in the bearings that gets pushed to the sides to let the balls run more freely new BB's can feel pretty draggy. Your UN26's will soon spin more freely. They may or may not eventually spin as nicely as the one in your newer frame and they may or may not last as long in poor conditions as the better UN54's.