The most notable — and the most significant — change between the initial release candidate version (RC0) of Hyper-V and the RTM edition is better performance. Most of the performance work was done between RC0 and RC1, but not many people knew about it due to (a) not-so-wide a release and (b) a ban on performance testing by Microsoft. The company just wasn’t ready for it to be tested on a wide scale. The performance story between RC1 and RTM is identical.
QLogic, a vendor of storage-area networks (SAN) and other components, tested Hyper-V RC1 on one of its own host bus adapters (HBA), based on Fibre Channel. QLogic hooked the HBA up to a storage array, to test the number of I/O operations per second supported by a virtual machine (VM) as opposed to real, physical hardware. The results were impressive, and are equally so under RTM, as the underlying performance plumbing didn’t change.