Sometimes when someone wants to get past a throttle of some sort they place the niceness of a process in the negative stage. The higher the negative number the higher the more priority.. This is a burden on servers that meant to have shared allocated resources.

Well, the solution. If this is a VPS and they all of their processes are set to -15 but the default is 0, issue this command:

for i in `cat /etc/passwd | awk -F: {'print $1'}`; do renice -n 0 -u $i; done