Download speed wasn’t really affected. But my uploading skyrocketed. I went from struggling to get 1.0 ratios to almost always getting 1.0 on even the most mediocre torrents.
The type of person to seed is more likely to open ports for this so if you didn’t have them open you’d be unaffected. But the type of person who mostly just leeches and doesn’t care about seeding probably wouldn’t notice because the seeders have their ports opened so they didn’t need to.