Torrent went from fast to slow. Why?

How many seeds and peers? Every seed has a copy of the entire file being shared. Every peer has a portion of the file being shared. Each can provide portions to you, as well as others. So, two things are at work here, the number of seeds and peers, and the number of people who are requesting the same shared file. The fewer seeds and peers, the more requests, the slower the system works. Bandwidth has to be divided among all requests. The bottleneck could be literally anywhere between your torrent client and every other client everywhere that is dealing with the same shared file. As for seeds and peers, you should see something like this: Y(X) a number along with a number in parentheses. The number in parentheses, X, is the total number of people who have received a copy. The other number, Y, is the number of those that are currently logged in to the torrent network. The lower the Y values, the fewer sources are available.

Probably. The torrent client should show the number of peers / seeders.