Extrem lange Ladezeiten oder Timeout

Hallo,

ich habe einen Server mit Debian 7.8 und Plesk 12.
Seit einiger Zeit brauchen Webseiten mehrere Minuten zum Laden, obwohl massig Kapazitäten verfügbar sind.
Folgend die Eckdaten:
CPU GenuineIntel, Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz
Version Parallels Plesk v12.0.18_build1200140606.15 os_Debian 7.0
OS Debian 7.8
RAM 32GB

Verbraucht sind immer nur rund 2GB RAM bei 0.2 Load

Hier ein Auszug aus der apache.conf:

Code:

---

# prefork MPM
# StartServers: number of server processes to start
# MinSpareServers: minimum number of server processes which are kept spare
# MaxSpareServers: maximum number of server processes which are kept spare
# MaxClients: maximum number of server processes allowed to start
# MaxRequestsPerChild: maximum number of requests a server process serves
<IfModule mpm_prefork_module>
    StartServers          5
    MinSpareServers        5
    MaxSpareServers      10
    ServerLimit          150
    MaxClients          150
    MaxRequestsPerChild 4000
</IfModule>

# worker MPM
# StartServers: initial number of server processes to start
# MinSpareThreads: minimum number of worker threads which are kept spare
# MaxSpareThreads: maximum number of worker threads which are kept spare
# ThreadLimit: ThreadsPerChild can be changed to this maximum value during a
#              graceful restart. ThreadLimit can only be changed by stopping
#              and starting Apache.
# ThreadsPerChild: constant number of worker threads in each server process
# MaxClients: maximum number of simultaneous client connections
# MaxRequestsPerChild: maximum number of requests a server process serves
<IfModule mpm_worker_module>
    StartServers        5
    ServerLimit                70
    MinSpareThreads      5
    MaxSpareThreads      70
    ThreadLimit          64
    ThreadsPerChild      32
    MaxClients          150
    MaxRequestsPerChild 1000
</IfModule>

# event MPM
# StartServers: initial number of server processes to start
# MinSpareThreads: minimum number of worker threads which are kept spare
# MaxSpareThreads: maximum number of worker threads which are kept spare
# ThreadsPerChild: constant number of worker threads in each server process
# MaxClients: maximum number of simultaneous client connections
# MaxRequestsPerChild: maximum number of requests a server process serves
<IfModule mpm_event_module>
    StartServers        5
    MinSpareThreads      5
    MaxSpareThreads      20
    ThreadLimit          64
    ThreadsPerChild      32
    MaxClients          350
    MaxRequestsPerChild 10000
</IfModule>

---

An welchen Parametern könnte es liegen? Ich komme leider kein Stück mehr weiter.

Vielen Dank im Voraus.