[DiapDealer]

Before we go down the path of disabling various things (though we may quickly get there) there's one quick thing I'd like @RbnJrg to try first.

Create an environment variable on your system named QT_OPENGL and give it the value of "angle". No quotes around angle if you're using a gui to create the variable. And then launch Sigil normally (no safemode). Let me know if the memory usage is any different.I

The easiest/quickest way is probably from a command prompt:

cd c:\program files\sigil <enter>
set QT_OPENGL=angle <enter>
sigil.exe <enter>