Even though I have just one site on my dual core server, the load still at 4 to 5 constantly with lots database connection errors. I love Wordpress, but it is bad with high traffic site. Why? Even with default theme and deactivate all plugins, the load it still high. I have 20000 visitors daily. Drupal and others are not as bad. Anyway, I installed e-accellerator from my host which help a bit but not enough.
I also installed WP-Cache to help with load.
But i noticed that the load now at 2 average and still was getting database connection errors. When i view source i noticed there was just <!-- Dynamic Page Served (once) in 0.690 seconds -->. No cached page served by.
So i researched and found that in wp-config....
" define('WP_CACHE', true); " MUST be under " // ** MySQL settings ** // " .
This is only apply to PHP 5.25. My other host with PHP4, this does not matter. define(WP_CACHE) could be anywhere under mysql settings.
So now this shows in my page source and load is now 0.25 at busiest time of the day
<!-- Cached page served by WP-Cache -->
I also learn that Wp-Cache does not show page cached page to logged in user and the anonymous user. pages are different for each user, so when checking, check while logged out.
Bye.