We have several Joomla 2.5 based sites hosted on ISPConfig all experiencing similiar difficulties. Pingdom (www.pingdom.com) is used for monitoring our sites at 5 minutes interval so we can keep track on when site is online/offline. When the problems start all sites don't answer at all and Pingdom shows timeout (<30 seconds for response). We suspect the problem might be in global Apache or PHP configuration, but we can not confirm this. The problem is similiar to this: http://www.howtoforge.com/forums/archive/index.php/t-59262.html Please help us troubleshoot this problem. This is how "top" looks when problems are happening: https://www.dropbox.com/s/s4oa6a98ti064m3/Screenshot 2013-11-14 14.03.05.png Restarting Apache helps.