The KeepAlive directive allows multiple requests to be sent over the same TCP connection. If you have a high number of elements per web page this can use up many TCP connections. You can reduce the overall number of TCP connections used by setting the KeepAlive directive to On.
The KeepAliveTimeout directive controls the amount of time Apache will wait for subsequent requests before closing the TCP connection. If your VPS cannot keep a large number of processes open due to limited kernel memory, you should set the KeepAliveTimeout to 1.
Once you make these changes, you will need to restart the web server for these changes to take effect.