Speed up slow save time in calc (x64) Win 10

LibreOffice calc can be very slow to save complex spreasheets. I’m a speed user in a work environemnt, and this causes a painful workflow distruption. I patiently watch the save bar crawl accross the screen while my mind and fingers race ahead on short cut keys and formulas to no effect - this is something other professional users may understand. For comparison, office 365 is very quick to save, almost instant over the LAN.

I am not a programmer, but why is there such a huge difference between the two programs in saving times?

Would it be naive to request a feature for Libre calc to allow mutli tasking - eg keep working on screen without disruption after Ctrl-s or autosave. Can Libre Office save a “shadow copy” or “image” of the file in the background ?

Version: (x64)
Build ID: 54c8cbb85f300ac59db32fe8a675ff7683cd5a16
CPU threads: 2; OS: Windows 10.0; UI render: default;
Locale: en-AU (en_US); Calc: group