High CPU usage and server load using Codeigniter

[eluser]Krzemo[/eluser]
I've been through performance tuning myself recently.
I guess noone will tell you much at lest not knowing how well you box is tunned. There are lots of options if its standard configuration: apache tuning (turning loggin off i.e. or changing it for Lighttpd), mysql tuning (starting from queries, indexes etc and finishion on configuration) and finally eaccelerator or xcache for PHP.

I wouldn't worry about MySQL, HTTPD or PHP doing 30% untill load average is not much higher then number of your CPU cores and you dont see website performance decrease (you can check requests response times in FireBux ie), unless you are expecting high traffic peaks soon...