If you live in Murica, I know there are some areas where you are locked into using shitty, throttling ISPs like Verizon.
Basically, they try to auto-detect torrent and p2p traffic, and either block it or severely limit the speed (slows it to a crawl). The usual way to notice this is that the speed starts out ok, and then within minutes it just drops to snail speed.
These fuckers are the ones lobbying against net neutrality: They basically want internet to be just an updated television system, where you are a dumb sheep watching what is spoon fed to you by commercial entities, and where websites like Youtube have to pay ISPs so their speed won't be throttled. Basically, these idiot ISP managers are trying to destroy all citizen driven internet activity, with the blessings of the fools in politics who write laws.
If you aren't throttled, it is also possible that either:
1. Your upload speed just sucks... This is particularly common if you have cable internet. On cable the bandwidth is limited, and shared between upload and download. So many ISPs like to sell ridiculous download bandwidths that you will never use, while hoping you won't notice the crappy upload speeds that go with them.
2. Your firewall or router might be getting in the way. If you have several computers at home, you are probably using NAT, which basically means all your machines have the same IP on the internet, and the router in your home has to figure out which connection should go to which computer. It's an old problem that your router maybe won't know to which machine it should send unexpected connection requests from the outside world, and that it therefore drops them. The torrent app should be able to auto-configure this for you, but maybe something is failing, or maybe your router/firewall is set to block random incoming requests to these ports. I don't know.