I've noticed that sending RCON commands to my dedicated servers (Linux and Windows) causes the CPU to spike over time as though the server is leaking threads. A simple loop issuing the
listplayers command is enough to reproduce this over several minutes.
Typically an idle server on my Linux box uses 5% CPU. After two minutes with repeated
listplayers RCON commands being sent in a single-threaded loop, I noticed the server process CPU usage had skyrocketed to 165%, and stopping the RCON commands did not reduce the CPU usage. It remained at 165% until the server was manually killed.
This behavior was tested and confirmed on a Linux VM and on Windows (both bare-metal and in a VM).
For what it's worth, this does not happen when RCON connections are declined due to an incorrect password.