Windows 8 news continues to trickle from the Building Windows 8 blog at a steady clip: today, Gabe Aul detailed changes to the Windows 8 boot process that promise to drastically reduce startup times.

The team wanted to come up with a startup method that would deliver the benefits of a cold boot (a "fresh session" at startup, no power usage when off) while reducing the amount of time that it takes to load the operating system from disk to RAM. 

To accomplish this, Microsoft has combined aspects of a traditional Windows shutdown with system hibernation, which saves the contents of your RAM to disk and then restores it to RAM at next boot. While a Windows shutdown currently closes all user programs (the "user session") and then all system services and processes (the "kernel session") completely before powering off, Windows 8 closes the user session and saves the rest of your RAM's content to disk. The kernel session can then be restored to RAM quickly at next boot - this is more speedy than traditional hibernation both because there's less data to restore to RAM from the disk (just the kernel session, as opposed to the kernel session and the user session), and because restoring hibernation files is a fully multithreaded process in Windows 8. If the feature works as well as it does in the Microsoft demo video, it is indeed quite impressive.

Microsoft notes that drivers are still initialized during this startup process, which means that driver and system updates should no longer require a "full" reboot of the system (something Microsoft has been promising since the Longhorn days). However, for those of you more comfortable with a traditional "full" shutdown, there are command line options to toggle the new feature on and off ("powercfg /hibernate off" which has the unfortunate side-effect of completely disabling hibernation), and also to initiate one-time full shutdowns ("shutdown /s /full").

According to Microsoft, these improvements should benefit users with SSDs and HDDs alike, and will be especially noticeable when paired with systems supporting UEFI, the BIOS replacement that is slowly being adopted by most major PC manufacturers and motherboard makers. For full details, as always, you can check out the very detailed post on the Building Windows 8 blog.

Source: Building Windows 8 Blog