[08-01-2017 20:08:58] NPCD: npcd Daemon (0.4.14) started with PID=30016
[08-01-2017 20:08:58] NPCD: Please have a look at 'npcd -V' to get license information
[08-01-2017 20:08:58] NPCD: HINT: load_threshold is enabled - ('10.000000')
[08-01-2017 20:09:54] NPCD: WARN: MAX load reached: load 11.280000/10.000000 at i=337
[08-01-2017 20:11:43] NPCD: WARN: MAX load reached: load 10.380000/10.000000 at i=927
[08-01-2017 20:13:43] NPCD: Could not create thread... exiting with error 'Resource temporarily unavailable'
[08-01-2017 20:35:15] NPCD: npcd Daemon (0.4.14) started with PID=6302
[08-01-2017 20:35:15] NPCD: Please have a look at 'npcd -V' to get license information
[08-01-2017 20:35:15] NPCD: HINT: load_threshold is enabled - ('10.000000')
[08-01-2017 20:35:43] NPCD: Could not create thread... exiting with error 'Resource temporarily unavailable
The correct file location should actually be /usr/local/nagios/etc/pnp/npcd.cfg as you have, and you need to run service npcd restart after for it to take effect.
I agree though, a load of 16 is somewhat high. How many hosts/services total are you checking? Is there any other application running on this server?