How to increase LibreOffice compression speed during saving?

LibreOffice saves *.od* files as ZIP archives, using DEFLATE compression. However, LibreOffice saves very slowly compared to Microsoft Office; the resulting files are usually smaller than Microsoft Office’s (marginal benefit).

Working with 1.5 MB uncompressed (~25 sheets, ~20 charts), LibreOffice Calc takes 10 seconds to save to a 265 KB file, whereas Microsoft Office takes 1 second to save to a 307 KB. The files are both .xlsx.

I do not want to wait 10 seconds between saves and I have a PowerShell script that uses 7-Zip to recompress the saved file with higher compression, negating LibreOffice’s size advantage (which was minimal, considering the extra time).

How to increase LibreOffice compression speed during saving?