What do you mean by "lot"?
For example, space to the left of item text is used/reserved for item icons (like ckeckbox or any user defined icon).
Space to the right of item text is used/reserved for the symbol signing the pop-up menu (see the attached picture)
So, what "space" would you like to reduce?
The only way I can think of is if the menu's owner-draw flag is set and you handle drawing and measuring manually. Altho maybe a menu HWND can be obtained through ::FindWindow("#32768",NULL) for MFC menus and some manipulation can be done on it but i dont think it is likely to work.
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