I've been running a pretty high pop website for a few months new and as its growing we've been having some problems lately.
Its a 2 core Xeon, 8GB, SSD server. We're pulling +- 150k people a day.
Its a lightning fast wordpress stack and up to about 450 concurrent (200 pageviews a minute) it remains lightning fast.
If it goes beyond that, the load goes INSANE, from 1.5 to 20 or 30! I've been trying to fine tune my.cfg but I'm about to give up, there is LOADS of information which is very varying, so I'm starting to get confused.
As you will see, it tells me to increase query cache, doing so however absolutely destroys my CPU even more and a lot earlier than when it remains at 8MB...
We also converted all tables to InnoDB and saw a big performance gain that way in the past.
I hope I can get some insight from professionals. I would even pay for some one on one time if needed.