What is the impact of enabling EVC on your vSphere Cluster?

http://www.vmware.com/files/pdf/techpaper/VMware-vSphere-EVC-Perf.pdf

Basically, the test results show that almost all workloads perform well even when the virtual machine presents an EVC mode that corresponds to an older processor generation. The EVC mode setting had varying impact on workload performance based on the ESXi hosts’ CPU instruction set features made available and their relevance to the workloads.

One workload, AES-Encryption, didn’t fare as well due to a dependence on special-purpose instruction sets only available in younger processor generations.