My site is currently having 70000 posts, and generate about 1.4 million views per month.
Specs are Quad-core Xeon, 8GB RAM, FCGI
Plugins: W3 Total Cache, Jetpack, WP Page Navi, Contact Form 7, Discuz, Events
Problem: Whenever my uploaders publish news, the server load will spike. and When 2 or 3 of them upload news at the same time, the server will hang for a few minutes (Internal Server Error) and then back to normal again.
Tried: Changing permalinks, changing to wpsupercache, optimised theme queries.
I've been having this problem for a year plus but still did not find a way to solve. Anyone have any idea? Thank you.
PS: All plugins and wordpress are updated everyday.