I was in a brutal single rider line last week, too. Not sure why but going up the stairs was dreadfully slow. It probably took me 30 mins just to get up the stairs, I waited longer for SR that day than I did ROTR and ST combined.I'm not sure you should try the single rider line.
The standby line was at 60 minutes around noon on Tuesday and we had lunch reservations at 1. I decided to do the single rider line -- didn't care that much about the ride itself, but wanted to see the Falcon interior -- assuming it would be much quicker. After 45 minutes of waiting, I had to go back out the entrance so we wouldn't miss our lunch reservation and based on the way the line had been moving and what I could see up ahead, I'd guess I had at least another 20 minutes of waiting if not longer. I would have been better off getting in the regular standby line.
That could have been a one-off situation except it happened again later that afternoon. Tried single rider again when the standby was at 55 minutes, and after 30 minutes of waiting I wasn't even close to riding. Based on where I was compared to where I was when I had to exit the line earlier that day, and how slowly the single rider line was moving, I'd say I had at least another 30 minutes to wait and probably more like 45. Ended up leaving again because I had other stuff to do.