The vCenter Server provides detailed CPU and memory usage statistics at the host and VM levels. Statistics include CPU usage and demand, and private, shared, ballooned, and swapped memory usage breakdown.
Viewing the statistics in the vCenter Server tab pages is one way to monitor CPU and memory performance. Using the esxtop command-line utility to periodically collect CPU and memory data is another.
Because insufficient CPU resources will reduce maximum throughput, monitoring CPU usage of high-throughput workloads is very important. If the CPU usage for a VM is consistently above the 50-70% range, add more vCPUs to the VM.