Speed problem (mostly with more than 1 torrent at a time)

[ChRiiLLe]

I have a 100Mbit/s full duplex fiber connection and can reach that speeds at booth download and upload, so there is no problem with my connection.

Mostly i can only download at about 3MB/s if i want to keep upload at 10MB/s. If i go to 4MB/s download or higher my upload speed decreases to about 1-3MB/s.

BUT, here's the weirdest part.. If i have one torrent seeding at about 6-7MB/s and then start another one or two torrents to download and cap the download at, lets say, 2MB/s.. The TOTAL upload for all torrents going down below 300KB/s :S

How come it is like this?

I'm using 1.6.1 since i think it gives me better speeds than 1.7.2. I have a Gbit ethernet card in my computer wich is a dual core opteron @ 2GHz with 2GB ram, so that shouldn't be the problem either.

I have the cache in uTorrent at 700MB with those three checkboxes checked:

Enable caching of disk writes

Enable caching of disk read

Increase automatic cache size when cache thrashing

[kurahashi]

AFAIK download capping is bugged since... always.