Changes

By providing unified scalable platform with such unique features as rapid application and updates provisioning. Each container is hardware independent and can be moved to another OpenVZ-based system in seconds over the network. This allows for ease of hardware maintenance (move out all containers and do whatever you need with the box) and improved availability (keep a synchronized copy of your container elsewhere and start it up when primary service failed). If your old box is not able to cope with peak load anymore, just move your containers to a new one.

Near zero. There is no emulation layer, only security isolation, and all checking is done on the kernel level without context switching.