Seemingly unnecessary activity

[Roman0]

Hello,

I've been using qBittorrent since v3.1.11, and had no major issues with it. After configuring it a little it worked perfectly. Same with v3.1.12, it worked fine right after the update. Only recently I started having problems. qBittorrent seems to be very active, even though all my torrents (84 at the time of writing) have already reached their threshold and are stopped. qBittorrent's CPU usage is quite high, commonly jumping around 10-15%, and that wouldn't be a issue if Microsoft Security Essentials didn't have a problem with qBittorrent.exe, but it's constantly scanning the process and using up ~15-25% of CPU. I had to add it to exceptions.

If that's not bad, this one is a showstopper: it chokes my Internet connection. Yes, the overall activity is low, but it doesn't play nice with Steam. Whenever qBittorrent is running I can't log in to Steam, and the server list times out (servers not responding). Mind you, I had this issue previously (in v3.1.11) and I managed to fix it by turning on queuing in qBittorrent (it worked in v3.1.12 a well, at least initially), but now it's doing it again regardless what I do in the settings.

A little help would be appreciated.

qBittorrent version: 3.1.12
Libtorrent version: 0.16.19.0
OS: Windows 7 6.1.7601
InetSpeed: 50Mbps Down/5Mbps Up

EDIT: Last time I've been using the Steam server list was 21st of march, and didn't notice anything wrong back then. So it's a very recent issue.

[ciaobaby]

it chokes my Internet connection.

Reduce the half-open connections to less than 20.

[Roman0]

it chokes my Internet connection.

Reduce the half-open connections to less than 20.

Was 50, I've set it to 10 then restarted qBt. No difference. Still interferes with other connections.

[Peter]

This happens to me with huge swarms.
Client does not matter, torrent size does not matter, nothing.
Just the swarm size.

If it's huge, then even if I have a miniscule upload/download speed set, my internet will just die.
What kind of swarm you are connecting to? Small ones?

[ciaobaby]

it chokes my Internet connection.

Reduce the half-open connections to less than 20.

Was 50, I've set it to 10 then restarted qBt. No difference. Still interferes with other connections.

Have you rebooted your OS and router to flush the TCP/IP stack on both?

[sledgehammer_999]

I am going to shoot in the dark and request you to do something that seems totally unrelated.
The CPU spikes might be caused by column sorting. Try setting(or resetting) the "#" column as sorting column. Did it make any difference?

[Roman0]

Sorry for the delay. I wanted to make sure it's not a temporal change.

After testing it for a day or so I must say, it calmed down. Both the high CPU usage and network issues are gone.

First I tried all the stuff ciaobaby told here, but there was no change. Then shiki suggested that the swarm size might cause the issue, and although I can't tell what's the size of my swarm I don't think that was the problem, as it happened just recently, and I didn't download stuff from any new sources. Then I tried sledgehammer_999's suggestion. Just clicked a couple of times on the "#" column label, then went back to sorting by "Added"... and somehow, it helped. Yes, it made a difference. CPU usage went down to comfortable <5% and I can ping Steam servers again. Thank you for your help!