On a relative scale, this time of day is absolutely horrible at Dulles, but, there's nothing you can do about that because of the European destination. I would get there at least two hours ahead regardless of screening. At that time of day, people are backed up just to get down the escalator. You'll also have to account for additional time to drop off your checked luggage and even more time if you want to stay there in case the screeners open it up.

I was just there earlier in the week. If you go through the security entrance closest to the parking garage, there are no NoS's in that area. I can't vouch for the security chackpoint right behind the United counters. I know there is one in the small "Black Diamond" lane downstairs near baggage claim. So, avoid that line at all costs. If you have an upgrade, you can go through the shorter line once you make it downstairs.