Libreoffice 5.4.4 Draw 100% cpu. Ubuntu 16.04lts

I am trying to edit a pdf file in libreoffice draw. If I try to select an area to cut or copy the program hangs and soffice.bin is using 100% of cpu.

I have sort of found the answer to this.
In options, memory I have increased the numbers dramatically as I have no shortage of RAM.
As I am cutting & pasting musical scores, if I select a smaller area at a time it works - slowly- but doesn’t hang.
(1 line of music can be over 150 drawing objects!)