Embassy time

Has anyone been to the embassy lately to get their kid(s)' US passport? We have an appointment at 9:15 on Tuesday. It's my understanding that this is the time we're to get in line for security. I know to get in the citizens' line, but I've been told on other boards that you can wait for 3-6 hours in line to get into the embassy. Is that accurate?! If you've been lately, what was the total time that you were at the embassy (arrival at the line to wait until you walked out of the building finished)?

I was thinking that we'd be out by 10:30 or so, but I think that must be too ambitious. I was hoping to do some quickie sightseeing (Westminster, Parliament, the Eye, maybe Tower Bridge, etc.) afterwards, but we have to leave by 1pm at the latest to get our rental car back in time in Leeds. Do you think this would be possible? Or are we likely to be spending all of our time at the embassy? 

I went in May and I got there about 30 minutes before my appt.  It was first thing in the morning, but I can't remember the exact appt time, maybe 9:00, so we got in line at 8:30.  When we got there the US Citizens Services line was maybe 10-12 people deep, including a few family groups.  By comparison the "Other" line was maybe 30-40 people deep already.  There are two sets of security machines, so the US Citizen line moves at it's own pace and isn't affected by the "others".  I would say from start to finish, security took 15 min.  Once inside, I remember needing to take a ticket and wait in another line to "check-in" for your appt.  This took another 10 min or so.  Then you just wait for your number to be called.  We were there for a couple of hours, but were definitely out before noon.  You should have time to do a little sightseeing.

I was there last week, also for a 9:15 appointment.  My wait outside to get in was probably only about 15 minutes, but the real waiting was inside.  I waited to give them my documents, then they told me to wait for an interview.  I was called up again after a long time and they checked a few things about my purpose in being there and my documents then told me to wait again for the interview.  All in all, I believe I was there for three hours. Bring food and toys for little one--there is a play area in the back thankfully. I received her passport and report of birth abroad yesterday.