The calculator gives some good suggestions that might improve your overall download speed. Just enter the maximum upload speed of your connection, and the calculator will give you your recommended upload speed (you can test it here), maximum connections per torrent, and some other settings. The calculator can be used for every torrent client.
The maximum upload speed is by far the most important setting. It might sound strange to some, but you should always cap your upload speed to reach the best download speeds. Your connection is (sort of) like a pipeline (or tube if you prefer), if you max out your upload speed the pipe will be fully used, which means there’s not enough space left for the files you are downloading. The calculator recommends to set it at 80% of your maximum, I agree with that. People with high-speed connections might go a bit higher, and set is at 85% or even 90%.
Some people find that when they are seeding, browsing the web becomes sluggish. This is due to a badly configured upload speed in their BitTorrent client. When you have the correct upload speed entered into your client, browsing the web is noticeably quicker and seeding becomes almost transparent.
How to configure your maximum upload speed?
Here at TorrentFreak we also wrote some post about optimizing BitTorrent download speeds, might be worth the read if you want to know more.
Read more on optimizing your BitTorrent Speed.