WP version is 4.1.1
MySQL version 5.6.28
MySQL query cache and OPcache isn't configured.
I already have WP Super Cache installed
Regarding the spike, what I noticed yesterday in MyPhpAdmin monitor, is that the ram usage was slowly rising, until it was all taken, then the cpu spiked.
You can see this here: http://i.imgur.com/xDHJ8qF.png