Thank you for your explanation. The first thing came in my mind was that nothing was told about opcache that was introduced in Moodle 2.6 in combination with PHP 5.5. in this page
I think not everyone is aware about that feature. I am running Moodle 2.6 and PHP 5.5 on CentOS 6 for a month now and I must say: the performance increased significant! It uses a lot more RAM but I am certain the CPU have to do less work. If I have to beleive our monitoringtool, the CPU is eating out of his nose! So, I assume our server uses less power, since the CPU have to do less work?
Maybe encourage people to make use of opcache? If that is possible: not everyone is in the position to do that for some reasons Like knowledge, shared hosting, bad ass support company
I am not sure my reaction makes sense, probably not. Neverhless, I regret that CPU upgrade now