Too long time for saving calc file

My calc file consists of around 400/30 columns/rows (80% empty), 15 dialogs and 1 module with around 6000 lines of macros. 220 K. When I save this file it takes around 30 seconds. I want to shorten the time of file saving. Is it possible? What does the saving time mainly depend on?

LO:
Version: 6.3.6.2 (x64)
Build ID: 2196df99b074d8a661f4036fca8fa0cbfa33a497
CPU threads: 8; OS: Windows 10.0; UI render: default; VCL: win;
Locale: fr-FR (en_US); UI-Language: en-US
Calc: threaded

Device:
Inspiron 3583
Processor Intel(R) Core™ i5-8265U CPU @ 1.60GHz 1.80 GHz
Installed RAM 8.00 GB (7.88 GB usable)

I guess, but you are the only one to know the file.

I’d think it is worth to try newer versions. Maybe “they” already solved your problem… (There are portable versions and paralell installs available to test…)
.
One observation from my files: First save is slower then subsequent ones.

Encryption, if used:
https://bugs.documentfoundation.org/show_bug.cgi?id=105844

Some general informations are found in older threads, like this:

Was the file created purely in Calc, or pasting external data?

Created purely in Calc.