Symptoms
Control Panel is performing slowly if accessed by branding name.

The following error is in web server log /var/log/httpd/error_log:

[Mon Aug 24 10:18:09 2015] [error] server reached MaxClients setting, consider raising the MaxClients setting

Cause
Number of incoming connections exceeds the limit of web server.

The web server has the limit of maximum connections defined in /etc/httpd/conf/httpd.conf:
…
ServerLimit 2
MaxClients 2
…

The web server stops handling the incoming connections until the previously established connections are destroyed.

Resolution
Back up the configuration file of web server:

# cp /etc/httpd/conf/httpd.conf{,.back}
Edit the file, having increased the limits for MaxClients and ServerLimit parameters of prefork.c module:
…
ServerLimit 20
MaxClients 20
…

Reload the web server configuration:

# service httpd reload
NOTE: By default the web server loads ‘prefork.c’ module, so the parameters of ‘worker.c’ are being ingnored and can be remained unchanged.