I can confirm the problems Mark is having.
Until recently I used 2.7.13. I didn't have many problems with downloading (average 20 kB/s), but when someone started uploading the downloading speed dropped to 1 or 2 kB/s, while uploading took 3 or 4 kB/s

I was thinking that a new version would solve this problem. But both 2.8.4 and 2.8.5 caused more problems than I ever had before. Without changing anything in my preferences or connection speed the downloading never exceeds the 1 kB/s. Uploading seems to be impossible.