The system CPUs cannot get deeper than the C1 state when the system is idle (sleep state). This can manifest itself in C-state thread wakeup performance latencies.
Workaround
Edit the /etc/grub.conf file to add the following kernel parameter:
intel_idle.max_cstate=0
Reboot your server.
This disables the default intel_idle driver and forces the kernel to use acpi_idle.
This issue does not exist for Oracle Linux 6.6 UEK3.