Q. What is the Azure Compute Unit (ACU)?
A. The Azure Compute Unit (ACU) is used to help understand the relative compute performance between different Azure series and size VMs. It is based on the A0 (extra small) having a value of 50. A VM with an ACU of 100 has twice the compute of a VM with an ACU of 50. A VM with an ACU of 200 would be twice that of a VM with an ACU of 100 and so on. This is detailed at https://azure.microsoft.com/en-us/documentation/articles/virtual-machines-size-specs/.