Computer Configuration > Administrative Templates > Microsoft Edge
Both
HKLM\Software\Policies\Microsoft\Edge
Enables window occlusion in Microsoft Edge. If you enable this setting, to reduce CPU and power consumption Microsoft Edge will detect when a window is covered by other windows, and will suspend work painting pixels. If you disable this setting Microsoft Edge will not detect when a window is covered by other windows. If this policy is left not set, window hiding detection will be enabled.