Every so often there will be something that slows a system down. There are a few tools that can help to identify which process is the cause of this slow down. One such tool is htop. Htop is an interactive and real time process monitoring application for Linux which will show you your usage per cpu/core, as well as a meaningful text graph of your memory and swap usage.
Read the full thing at http://www.deonsworld.co.za/2012/12/20/understanding-and-using-htop-monitor-system-resources/
htop is available for both Mandriva and Mageia