Hello Julian/Mark,
A work-around was included in Hauptwerk v5.0.0 for it. Here's the relevant entry from the v5 changes section in the release notice:
PCs: organs should unload much faster on recent Windows 10 versions if Windows' page file is completely disabled (as a work-around to a performance bug relating to locked memory in recent Windows 10 updates, which Microsoft is aware of and aims to address properly in the longer-term).
This step in the the Hauptwerk installation instructions in the user guide covers how to disable the Windows page file (which I'd definitely recommend doing):
Step 2. (optional, for computer experts): Especially with recent Windows 10 versions, disabling Windows’ page file can allow organs to load faster, and unload much faster. However, doing so will prevent Windows and other applications from being able to use more (virtual) memory than your PC actually has RAM, so might adversely affect the performance of the computer when used for purpose other than Hauptwerk. Hence if your PC is used exclusively or mainly for Hauptwerk, or if you have plenty of RAM, you might wish to disable the Windows page file, for best Hauptwerk performance. To do so in Windows 10: go to Windows’ Settings via the Start menu, select System, select About, click System info, then click on the Performance | Settings button on the Advanced tab. Select Adjust for best performance, then click the Advanced tab. Click Virtual memory: Change and ensure that No paging file is selected (for each drive, if your PC has more than one), then click Set. Finally click OK on all of the windows and re-boot the computer if you changed any settings.
Best regards, Martin.
Hauptwerk software designer/developer, Milan Digital Audio.