There was a long period of time where LibreOffice Writer had severe performance regressions due to a rework of graphics handling that removed most of the image caching. If you had a slower system or a high DPI / Retina display it could be agonizingly slow due to constantly rescaling images on the CPU. It started sometime in either 3.x or 4.x and didn't get resolved until mid ~7.x. I stayed on an old version for a long time.