I find you're only as fast as your 1) home isp connection and 2) torrent peer(s).
Sometimes your speed as only good as your isp, particularly depending if your isp is hating on your torrenting. Comcast has been known to rate limit torrents actively, thus net neutrality debates were born. I find using CenturyLink, it is always oversubscribed in their local peering, so things tend to be a bit slow at first, but otherwise window up fast to max bandwidth if enough peers. Cox charges bandwidth overages now, but their service (internet peering) is generally better quality. I don't like random surprise overages after watching some 4k movies, so I'm now with CL with no caps.
You should never, ever get torrents from your direct home IP. Just don't - you are inviting problems. Get a reliable, trustworthy vpn service. This influences again how fast you are downloading, make sure your vpn gives you good speed too.
Almost any residential service, dsl or cable are asynchronous transfer rates, meaning faster to download than upload. Interesting thing with cable particularly, uploading at capacity tends to influence your downstream rates in bad ways. If you are maxing out your upstream to seed, your downloads are likely affected in some way. It's a long answer why, read up on docsis if interested. Limit your upstream rates in your torrent client/server to a respectable number is the short of this.
Torrents tend to create a _lot_ of packet per seconds and connections - make sure your router/firewall can handle this. I've seen torrenting kill enterprise firewalls in session/pps counts. Connection counts affect memory, and might/will kill a cheapo router. I see this occasionally with customer "incidents" when doing network/security consulting, and finding someone doing something stupid like installing a torrent client on their work computer as they end up being a top-talker I find with simple source flow counts for *abnormal* traffic. I've also had roommates kill my firewall doing this, before I find, block, and threaten them with no internet access ever again.
I don't find a lot of other optimization of clients are necessary. I use a transmission-remote server and otherwise feed everything through that as a server appliance from numerous clients on the lan (desktop, laptop, phone, sometimes remote), and all torrent collection show up as from an eu country via my vpn service. Above guidelines are quite good for my purposes.
-mb