I've had commutes like that. Sometimes it's low tire pressure which can dampen "road chatter" between the pavement and the bike, making it feel slower. (Same with my bikes with fatter tires.) Sometimes it's just me...I'll feel sluggish, but my legs are still strong. It's better than the opposite where I think I was flying, but the data shows the opposite. But the worst is when I feel slow and I am slow.