With respect to Windows 10 and LibreOffice fonts there is an interesting note here for LibreOfficePortable from PortableApps: LibreOfficePortable Font Warning. Basically it says that Windows 10 is bugged regarding font handling.
There is a section that says this:
LibreOffice Fonts - The LibreOffice
Portable package includes the
OpenSymbol font included with the
local version but not the other font
faces. This is due to a bug on Windows
10 Anniversary that causes dynamically
loaded fonts to take 10x longer to
load. The fonts are available as a
direct download zip of fonts. You add
the fonts to LibreOffice Portable
directly by placing them in the
LibreOfficePortable\Data\fonts
directory or add them to the
PortableApps.com Platform for use by
all apps by placing them in your
PortableApps\PortableApps.com\Data\fonts
directory.
It MIGHT be the case that even though you are fully installing LibreOffice to the system this will be an issue. (The same sort of thing is noted for ApacheOpenOfficePortable.)