How do I increase the speed of the system?

The speed of VMware VirtualCenter will primarily be based on the assigned resources of the system. You can always add CPU or Memory resources if you are running into an issue with those. You can also reduce the amount of data that you are collecting or holding on the system if that is what you believe to be slowing you down. I would recommend the vCenter Appliance if you are able, as the speed of it is incredibly fast in comparison to the alternative. In any case, I would recommend contacting VMWare support for any issue with slowness. Another thing I would highly recommend is to participate in VMWare Skyline for your systems to stay on top of any issues with your overall environment.