I have been chasing a memory leak in Oracle VirtualBox 7.0.x where a Windows 10 guest on a Windows 10 host has an ever increasing Virtualbox GUI host process Working Set memory. The WS memory seemed to increase more rapidly whenever there was window activity including simply waving the mouse pointer over an otherwise completely inactive guest host window.
Eventually diagnostic trouble shooting in the guest VBoxHardening.log file showed repeated rejections of DisplayFusion's attempt to DLL hook into the process. It turns out that each one of these caused the Virtualbox GUI host process to consume a little more host memory that it never released. Shutting DisplayFusion stops the memory leak. This leak was growing to over 32GB! in a matter of 24 hours.
The issue is probably a defect in VirtualBox itself rather than DisplayFusion. I am noting it here to help others avoid spending the ridiculous amount of time I have spent troubleshooting this.
Setting compatability to disable application hook linking for the VirtualBoxVM.exe process eliminated the problem for me.