It's gotta be the shoes

So I've noticed that since I got my new shoes about a month ago, my pace has increased. And not just a little bit. I am averaging 15 to 20 seconds per mile faster. It's really weird. I have tried to slow down, but it doesn't work. It just won't take. I don't know what it is. I'm not really complaining, I'm just slightly surprised that shoes can make that much of a difference. It's not like I was running in crappy shoes before and then switched to real ones or anything. I just switched models of running shoes. Very strange...