I tried resetting my user profile (by renaming its folder so that a new one was created), but it had no impact upon the problem. Tbh this does not really surprise me, because I do not really see this as a performance issue that could be fixed by some sort of profile cleanup. An office program like LibreOffice usually runs in a performant manner on systems with a fraction of the performance on my machine, so my computer should easily be able to compensate for any profile inefficiencies (which is also why LibreOffice itself starts up lightning-fast even though I did not install the pre-caching functionality (I dislike programs loading part of themselves into memory on bootup just in case they will be used; imagine if every program did that).
This is the weird thing: Picking such a simple menu entry lasts equal or longer than starting up the whole LibreOffice without having cached anything up front! And that is why I consider this more as a bug than as a regular performance issue.
The delay does not apply to every menu item. Primarily items in the Format-menu (character, paragraph, page) are affected.
My system:
Windows 7 x64 SP1, no virus scanner (but also no infection, trust me on that one), latest patches on everything, Microsoft .NET framework 4.5.2, Java 7 Update 72 (but I believe to have disabled anything in LibreOffice that would use Java)
Relevant hardware specs are in the original text above.
