There are various reasons why CSF firewall may make your WHM / server slow. Here are some personal tips from me.
If you are using WHM & CSF, under CentOS, you may follow this steps to change SSH port from 22 (default) to something else 🙂
To install ConfigServer Security & Firewall (CSF) in WHM, please run this commands in your SSH terminal one by one. wget https://download.configserver.com/csf.tgz tar -xzf csf.tgz cd csf sh install.sh After it completes, there is a new menu in WHM which is under “Plugins” category, named “ConfigServer Security & Firewall”. 🙂