qBittorrent official forums

I like qBittorrent, I think it is the best torrent client out there, but I've noticed that in some cases it absolutely hogs the CPU to the point where the mouse freezes and the audio stops working for a moment. It lags the entire system. Is there something wrong on my end? is qBitorrent suppose to be like that? I running an old 3570k running at 4.0Ghz

Most likely something on your end, what i do not know. Bad config, bad install, user error, it could be many things. Even if the platform is old it's still fine, i use a 35w apu and it does the job.