You don’t need VCB... If your backing up without VCB we use the esx host to compress the VMDK files. So , we will use a small amount of CPU on the host. We also use the network to send the backups.
If you use VCB and vRanger together we will backup over fiber and not use any CPU on the esx host to compress the VMDK files.
So, no CPU and no network traffic when using VCB and vRanger together.