After walking beagles for a couple years I found that sometimes carrying a treat or two in your pocket helps hurry them along or rather focus their attention on you. For example if he stops too long ask him to "come","heel" or say "here" whichever command you think is best and when he comes start walking and give the treat as soon as he gets to you. So you're not rewarding him for stopping to sniff but for comming to you and following. Or modify what you think you should do what I just suggested. Different things work for differnt owners and their fur children.
~Dione