I don't have many hard and fast rules in my life, but one that I've learned through painful experience is this:
Never Update a BitTorrent Client
Version 1 of every bittorrent client is lightweight, fast, and does nothing besides torrent your bits. Version 4 is 400gb, takes 30 seconds to load, shows ads, installs a rootkit phoning home to the NSA and mines bitcoin in the background.
This is an inviolate for bittorrent clients. There never has and never will be an exception.
Then there is transmission: https://github.com/transmission/transmission