It was very lax. Don't get there too early otherwise you will have to sit and wait by the securtiy stand until your start time. The security guy outside told me there was a cafeteria to hang out in inside the building, but once I got in there they told me I just had to sit and wait.
On a side note, there is no reason to stress out about the PEPC. Everyone there is extremely friendly and helpful. Whatever issue you have, the will do what they can to accomodate it. Seriously, it is more like a "let's get you hired" clinic than it is an interview and screening process.