What do you mean cpu time? cpu time in windows?
If the CPU RDY is low then contention or cpu resources would most likely not be your issue. I would look at your cpu wait time then minus the cpu idle if the remaining number is high then there is IO operation that is slowing it down disk? memory?
NUMA should be looked at but if your running 16 vCPUs then ESXi will make the NUMA visible to the guest so it can use it more efficiently.