If a VE has a very low cpulimit, it can have a high load despite low amounts of work being done (high amount of idle cpu %). Due to this, the HN load can be very deceiving.

For example- take a VE, set cpulimit to 2, start it, and run 100 cpuburn processes inside. now look at you HN's load and also the idle/user cpu %. you will see the cpus are doing almost nothing yet the load is around 100.