I have been using StableBit CloudDrive for around a month on a dedicated server.
The upload speed is always between 0 and 200 Mbit/s per drive with an average of 150 Mbit/s.
Since build 220.127.116.113 BETA the download speed maxes out on 10 Mbit/s which results in stuttering videos with PLEX and extremely slow copying.
The number of threads doesn't seem to matter, I tried 2, but I also tried 5, 10 and 20.
I also tried another Google account, but that also doesn't help.
I tried both a drive block size of 10 and 20MB, but it really seems to be a bug with the software, because changing settings doesn't help a bit, the download speed does not improve.