For historical info - Oracle bought OpenOffice and started to close it down, so all the developers that worked on it forked it into LibreOffice
Oracle has since given OpenOffice to an open source group, Apache, but the main development still happens on LibreOffice
-O2 vs -O3 adds
-fgcse-after-reload -fipa-cp-clone -floop-interchange -floop-unroll-and-jam -fpeel-loops -fpredictive-commoning -fsplit-loops -fsplit-paths -ftree-loop-distribution -ftree-partial-pre -funswitch-loops -fvect-cost-model=dynamic -fversion-loops-for-strides
I don’t think any of these optimizations require more modern hardware?