Coba cek nginx access log nya supaya tahu siapa yang sedang akses website... (jika diduga kebanyakan kunjungan ke website).
Load server tinggi bukan karena banyak yang akses saja. Bisa jadi script phpnya yg tidak efisien, database, dll.
ini Tuan
ini web server nya
2015/06/14 00:56:25 [notice] 1297#0: start worker processes
2015/06/14 00:56:25 [notice] 1297#0: start worker process 1301
2015/06/14 00:56:25 [notice] 1297#0: start worker process 1300
2015/06/14 00:56:25 [notice] 1296#0: using the "epoll" event method
2015/06/14 00:56:25 [notice] 1296#0: nginx/1.6.2
2015/06/14 00:56:25 [notice] 1296#0: getrlimit(RLIMIT_NOFILE): 1024:4096
2015/06/14 00:56:25 [notice] 1296#0: built by gcc 4.1.2 20080704 (Red Hat 4.1.2-54)
2015/06/14 00:56:25 [notice] 1296#0: OS: Linux 2.6.32-431.el6.i686
2015/06/14 00:55:37 [notice] 1301#0: exiting
2015/06/14 00:55:37 [notice] 1301#0: exit
2015/06/14 00:55:37 [notice] 1300#0: exiting
2015/06/14 00:55:37 [notice] 1300#0: exit
2015/06/14 00:55:37 [notice] 1297#0: worker process 1301 exited with code 0
2015/06/14 00:55:37 [notice] 1297#0: worker process 1300 exited with code 0
2015/06/14 00:55:37 [notice] 1297#0: signal 17 (SIGCHLD) received
2015/06/14 00:55:37 [notice] 1297#0: signal 15 (SIGTERM) received, exiting
2015/06/14 00:55:37 [notice] 1297#0: exit
2015/06/13 11

49 [notice] 1297#0: start worker processes
2015/06/13 11

49 [notice] 1297#0: start worker process 1301