I just got a pretty strange one. It's also not reproducible so I'm not sure what went wrong.
I opened the database to have a look and see what might be taking up all that memory (which might point to the fault). Opened every single table to check.
Nothing appears to be out of hand. 89 551 commander names gave me a shock, but that's the same in my pre-incident control.
After I quit, despite telling Access to not save changes, the database shrank to 24 324 kb and the backup control shrank to 22 412 kb. So there really seems to be nothing in that one hundred mb.
EDIT:
in any case, my game runs perfectly fine and there's nothing, so I guess it's just a strange glitch?
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OT:
Under research categories, which unsurprisingly is the techtrees list, I found one called
"Nova Cannon". What the heck is THAT? o.O
Spoilered... just in case.