I am having the same problem. The sink, pipes, vent and everything are brand new. It was a kitchen remodel where the sink location was moved to the other side of the kitchen. The old stuff was very old so we replaced everything and ran a new drain line. So it's impossible to be clogged. It has drained ultra slow since day one. Ours is set up exactly the same as in the picture ruditeesen posted except we have a dishwasher coming in on the left side. Also, occasionally, when it's draining so slowly a big air bubble will pop up out of the right drain. I think it's a venting issue. This is driving me crazy! When I run the water, my sink fills up and all the floaters stick to the sides of the sink as it very slowly drains! Very annoying!

RJ,
You piggybacked on a old thread so I moved you up to one of your own,

occasionally, when it's draining so slowly a big air bubble will pop up out of the right drain
This sure sounds like backpressure to me.
Backpressure is caused by a partial blockage. The discharge goes down and hits a partial blockage. Them discharge stops and bounces back sending a bubble of sewer gas ahead of it. Of course the drain action stops also and the discharge will slowly drain away. There's something down there blocking the flow.

I think it's a venting issue. To check for that remove the AAV and run some water down the drain. Recheck your work. Something's causing your back pressure. When you find that I Think your problem will be solved. Good luck, b Tom