Often, while I'm downloading something through qBittorrent, everything else slows to an absolute crawl -- YouTube and other web browsing, etc. I use an external device that provides combined wifi/bluetooth, and whatever qB is doing is so extreme that it'll often disconnect my Xbox controller, or sometimes even crash the device altogether, so that I have to pull it out and plug it back in.
I have download speed uncapped, but this happens even when my download is going at a measly 1 or 2 Mbps -- in fact it seems to happen more in that case than it does when I'm getting a nice respectable 10-15 Mbps. Upload speed is capped at 1000 kbps, and I haven't made any other changes to the default connection settings. Running on Windows, if that matters, and I've had the same problem across a couple version numbers. Really hoping this is something I can just fix in the settings.