qBittorrent official forums

Here's the thing: I fucking love qbittorent. I tried everything else, bit nothing comes close to it. There is one small problem: it uses a lot of my CPU and it makes the audio crackle. I have a 3570k with 8GB of RAM

I am a novice but this sounds like a latency issue. Maybe you can try determine the source of high latency with a tool such as "LatencyMon"(win7+) or "dpclat" while waiting for a professional reply. It might be a buggy network iface driver or storage controller driver.

I had the same problem, but solved successfully with the following steps:
1. Use all the processor cores:
Qbittorrent->Settings->Advanced Settings->Async I/O threads: 8
It helps to use your hardware better - but it won't fully solve your problem

2.
Turn off windows memory compression
This relatively new windows feature always compresses all the data that downloaded and sometimes the cached data when uploading.
Windows->search for Powershell->start as admin->after start type without quotes: "Disable-MMAgent -mc" and reboot
https://superuser.com/questions/1000485 ... ompression

Your downloads will be super fast and the cpu usage will be normal -> no crackling in sounds, less power usage and all the other good things
Notification: If no compression turned on, your computer will use more memory but you can live with it.

I'm also having this problem as well.  It only happens while a torrent is actively downloading.  Also, my whole system grinds to a halt ( slow mouse, window focus changes, audio garbling, etc ).  I love qBitTorrent, but its making my computer so I can't do anything else while it downloading.  Started about 2 weeks ago I think. Win 7 Pro SP1.