Ubuntu – Bittorrent is very slow

The problem, in your case, is probably not the data rate but the number of connections. Many internet gateways can't handle many connections at the same time.

You can Limit your maximum amount of simultaneous connections in the Transmission preferences like so:

Try to keep these values very low at first. 5/10 is a good starting point. And increase them slowly as you find it working.

• Note: Especially new torrents can show this behaviour. If you wait until there are enough seeders for a torrent, it'll be slowing down your browsing much less.

• Note also: You shouldn't have to limit bandwidth. This is handled by the TCP/IP stack, no problem, in most cases. It tries to schedule packet delivery fairly.

If you are using a router, make sure that the port used by Transmission for incoming connections is opened in your router (NAT port forwarding). As the other clients are faster, I suspect that they use a port that is already opened in your router.

In Transmission go to Edit > Preferences > Network and set the same port as in the other clients, and disable "Pick a random port every time Transmission is started". You can use the "Test Port" to see whether the chosen port is open.

It's also possible that your router is configured to accept UPnP or NAT-PMP port forwarding requests. If that is the case, you could enable the "Use UPnP or NAT-PMP port forwarding from my router" checkbox (instead of setting the port and opening it in the router manually).