[ubuntu] LibreOffice very slow on Ubuntu 16.04

Upgraded to Ubuntu 16.04 a while back & LibreOffice was obviously upgraded at the same time. Since then, LibreOffice has been very slow/unresponsive, greying out for extended periods at times. This is despite the size of the file (so it's not specifically related to another post here). I uninstalled/re-installed, purged/reinstalled & purged/installed the recent RC version all with the same result. It worked fine with Ubuntu 15.10 & the previous LO version. I have configured LO according to most suggestions (checking/unchecking graphics settings, etc.) with no change. I have noticed that without libreoffice-gtk it seemed much faster, but looked like something out of 1992.

I have a Toshiba C55t laptop with integrated Intel graphics.

Does anyone have any suggestions?