As far as BitTorrent itself goes, your optimal speed is also going to depend a bit on your client and the number of peers in the swarm.
Suppose you’re seeding a file to 3 peers. It’s not very efficient if your client uploads part 1 of your file to each peer, then uploads part 2 to each peer, etc. A more optimized upload would upload part 1 to peer A, part 2 to peer B, part 3 to peer C, etc. Then the peers can share each of those parts with each other. This way you are effectively only uploading the file one time before other nodes start seeding as well.
The thing is, this sort of seeding only works well in specific situations, including when there’s only one seeder, etc. And not all clients support this. Take a look at qbittorrent’s super seeding option for an example of one client that does.
As far as BitTorrent itself goes, your optimal speed is also going to depend a bit on your client and the number of peers in the swarm.
Suppose you’re seeding a file to 3 peers. It’s not very efficient if your client uploads part 1 of your file to each peer, then uploads part 2 to each peer, etc. A more optimized upload would upload part 1 to peer A, part 2 to peer B, part 3 to peer C, etc. Then the peers can share each of those parts with each other. This way you are effectively only uploading the file one time before other nodes start seeding as well.
The thing is, this sort of seeding only works well in specific situations, including when there’s only one seeder, etc. And not all clients support this. Take a look at qbittorrent’s super seeding option for an example of one client that does.