mpm_event limits

Perhaps use the suggestions here:

StartServers 2
ServerLimit 16
MinSpareThreads 75
MaxSpareThreads 250
ThreadsPerChild 25
MaxRequestWorkers 400
MaxConnectionsPerChild 10000

The Debian defaults in /etc/apache2/mods-available/mpm_event.conf:

<IfModule mpm_event_module>
        StartServers                     2
        MinSpareThreads          25
        MaxSpareThreads          75
        ThreadLimit                      64
        ThreadsPerChild          25
        MaxRequestWorkers         150
        MaxConnectionsPerChild   0
</IfModule>