Very slow downloads even with fast uploads

[bonny1992]

Deluge Version: 1.3.6
Libtorrent Version: 0.15.10.0
Operating System Version: Windows 8 x64 Pro

Plugins Enabled: Only WebUI
WebUI, Console or GTK: WebUI or desktop view
Web Browser: Chrome, Firefox
Filesystem: NTFS
Installation Type: Installer taken from official site

Hello,
I ask sorry for my bad english in advance.
I have a 1gbit server but I can't reach highspeed downloads, but for example my upload speed is very fast (for example, now it's 33kb/s DW - 1MB/s UP).
I tested with some of the Ubuntu, Lubuntu, Xubuntu ISOs and I can't reach any above 20MB/s even when via direct download I can reach 117 MB/s (proof: http://image.bayimg.com/c97990c693e4589 ... 92a098.jpg)
I have the default configuration of Deluge.
How can I reach better speeds?
Feel free to ask any other informations if needed!
Any help is very appreciated
And sorry again for my very bad english xD

EDIT: I forgot to say that my problem is present even with torrent with 6k+ seeds :\

[ElectronicWar]

Check if you hit the the connection limit (it's 200 by default) and increase it if it's maxed out.

[bonny1992]

And what limit should I put? Now I tried with 2000, i don't know if it's too low, too much or right.