It really depends on traffic and things have become very light. The shuttle between terminals runs every five minutes or so. The big question is getting through US pre-clearance - it can take an hour or just a few minutes. I've seen people get through the line if they have a flight to make by asking politely. Or if your airline starts yelling for your flight (which they're not supposed to do - NW never yells, DL and AA do. I've never heard calls for HP.)