Performance Optimization
After the initial creation of your Virtual Machine there are a number of performance tweaks you can make to your Guests .XML file and/or the Host system to greatly increase the Guest's performance.
hugepages
Hugepages are a function that lets the system kernel use larger pages when reading or writing information to memory (RAM). When this is enabled and the Guest is configured to use them the performance can be greatly increased. How to enable Hugepages depends on your GNU/Linux distribution.