[Libreoffice] Memory tweaking Graphics Cache tot avoid crash after deleting a graphic

Can a developer  explain how the Memory tweaking for the Graphics Cache 
is working.

I found that LO 3.4 can crash after deleting a Graphic in a document who 
contains  many or  a few Big pictures.
We  replace LowResolution Graphics with HighResolutions just before 
final printing . When the document is Loaded with HighResolution 
graphics, then LO "can" crash when deleting a Graphic.
This do not happens with OO 3.3 !
I supose it happens when i delete a graphic on a page where the size of 
the graphic if bigger than the setting of the "Memory per Object" in the 
UI Graphic Cache settings.
PLaying with the Cache size and the size per Object can avoid the crash, 
but there is no clear line why and when it happens.

so:
whats the meaning of "Use for LO" (who is max 256 MB)
whats the meaning of "Memory per Object" (who is also max 256 MB)

There are already many Issues posted for related Graphic 
deleting-disapearing problems

Greetz
Fernand