Insiders who are in the Skip Ahead ring will now be flighted Redstone 5 builds instead, with today's first preview rolling out as build 17604.
As the name implies, this is a step up for people for whom even the High Performance mode isn't enough - it throws power management out the window to eliminate "micro-latencies" and boost raw speed.
It appears that Ultimate Performance mode may only be available when a laptop is plugged in (or not on laptops at all), as Sarkar notes that the "power policy is now not available on battery powered systems".
Redstone 5 preview testing has only just begun, so it should be a little while before any big new features start making their way into Insider builds.
The latest Windows 10 preview build for Pro for Workstations includes a new mode called Ultimate Performance Mode. If you aren't up for bugs, you can opt out of Skip Ahead back to the Fast ring. Well, there's nothing huge here, with some emoji getting an update, and the expansion of Windows app permissions to let the user decide which UWP apps get access to Windows 10's full file system. The new plan, which users can select as soon as they update to the newest version of Windows 10, will prioritize performance over energy efficiency, and will consume more power as a result.
Or, as Microsoft puts it: "Over time, we've amassed a collection of settings which allow the OS to quickly tune the behaviour based on user preference, policy, underlying hardware or workload".
Furthermore, when Windows 10 Pro for Workstations is initially set up, it will now offer business and productivity-focused apps, rather than consumer-targeted software and games, which certainly makes sense. It will not be available on battery-powered laptops. This was one of the top feedback shared with us by our partners and users and we're delivering this in our next update.