It is common to use resource pools to create a folder structure in the host, have a cluster view of vCenter, and categorize your VMs. Administrators may place these VMs into these resource pools for sorting, but this is not the true sense of using resource pools. Resource pools should be used to prioritize VM workloads and guarantee and/or limit the number of resources available to a group of VMs. The issue is that even though a particular resource pool may have a higher level of shares, by the time the pool is subdivided, the VM ends up with fewer shares than a VM that resides in a resource pool with a lower number of shares.

If you create a resource pool with the default settings, then by default, this resource pool will be assigned 4,000 shares. Also, a VM has a default of 1,000 shares. In this way, if you place three VMs on a resource pool, even with default settings, the resources will be divided by three. This means that each VM will get one-third of the resources assigned to that resource pool by default.

Now if you take one VM out of that resource pool, it will have a performance impact.