I have a 256K/128K DSL connection, but it seems that most of my downloads come only at 4KB/s (unless downloading from multiple hosts). Also, they shift between the normal (2-14KB/s) download speed every other second, and the rest of the time 0 KB/s.

My uploads don't work at full speed either. Most of them do only 2KB/s, but at their best, they can be up to 8KB/s.

I am almost always connected to about 4 supernodes, that should not use my bandwidth too much.

How come doesn't my bandwidth be fully utilized?