Do you really get what the pictures mean?
Something like this could happen if you share small number of not very popular files. With 64kB/s the limit should be like 50kB/s. If you did not set it but use USS, and always have only 20kB/s total upload, then I'd think that USS does not work properly in your case.
The actual speed of each slot depends on the downloader's side no less than on uploader's: sometimes you have to upload really slow.
Perhaps it would be a huge surprise for you, but official eMule for a long time has upload manager. In real time the manager tries to spread evenly all the available bandwidth so that every slot gets equal speed. If, for example, one slot can accept only 2kB/s instead of 6kB/s, then all other slots would be able to receive additional 4kB/s - again, divided between all the remaining slots.
This post has been edited by fox88: 30 December 2011 - 03:33 AM