I found the solution for my problem.
Because I had some problems with my proxy, I changed it to a socks5 proxy from PIA. Because of this Radarr and Sonarr can't connect with qBittorrent anymore. I changed it back to the HTTP proxy from qBittorrent and it is connecting again. Also the high CPU usage is gone.
I made a stupid mistake but I hope someone can learn from it as well if they have the same problem. Thanks Binhex for your help and great docker containers.