It just scrapes along. I saw an on line review which said it was important to oil the fuck out of the chain, so I did, so it's really very, very lubed in there. I did a decent ride today - couple of hours, into Monmouth, round town to do some errands and back - and it's effectively silent. I was quite surprised - if there is any noise it's lost in the wind & tyre noise. The bike's as silent as a well-maintained fixed in direct drive, and just ticks quietly in top. It doesn't feel draggy either, though I'm sure there is some.
edit: I took some care to get a good chainline as well, which I think helps, as does having a decent and rigid chainring. You can't get heftier than that wee Goldtec