I have a dedicated server runs debian 6, nginx 1.07, php 5.3 with php-fpm and percona mysql 5.1.
I just set up the server recently and only 1 site runs on it.
The problem I encounter is that even I have 10 php fastcgi processes set but 1 php5-cgi process consumes 100% cpu while the other 9 consume almost 0%. At this time, whole server is slow and so does the site.