Microsoft is releasing a cumulative update for its Windows 8 operating system today ahead of the general availability on October 26th. The update, around 170MB, includes power and performance improvements, alongside some fixes for audio and video playback in Windows 8 and the usual application and driver compatibility updates.

"During the final months of Windows 8 we challenged ourselves to create the tools and processes to be able to deliver these "post-RTM" updates sooner than a service pack," says Windows chief Steven Sinofsky. The updates are being delivered today via Windows Update to existing Windows 8 users. Microsoft is also rolling out a number of updates to its built-in Metro style apps for Windows 8, including improvements for the Mail app for conversation view and an update to support Xbox Music in Windows 8.