Hello there,
I've a very high Load Average ( 12 on a 4 CPU - 8GB Ram VPS ) and a low RAM/CPU use, also iotop looks ok.
How to determine the reason of the high load?
ps aux | sort -nrk 3,3 | head -n 20
will show you the top 20 processes by cpu load. This will probably reveal the user account or website that is the culprit.