why is calc randomly crashing after upgrade to LO 6.4.4

Upgraded from 6.4.3 to 6.4.4 on a PC with Ubuntu 18.04. While Calc would hang for a suffering but tolerable minute or two with high CPU usage the latest installed version of 6.4.4 crashes and forces a recovery.
I moved the same spreadsheet to a freshly installed Ubuntu 20.04 OS on another partition but the same PC, same hard drive, and it hangs but does not crash with a 6.4.3 LO.
Why does the hogging of 1 CPU occur and continue now to the point of crashing at least Calc? Is there something configurable that can be done? It is so frustrating.
Given:
Memory 15.6 GiB Processor AMDO Ryzen 5 2600 six-core processor x 12 Graphics Radeon RX 570 Series (POLAR1510, DRM 3.35.0, 5.4.0-… Disk Capacity 1.0 TB

Test user profile causing the issue:

  • Start in Safe Mode using Help -> Restart in Safe Mode and confirm the restart using button: Restart
  • Archive your profile expanding Advanced (click on the word Advanced right above Help button) and click Archive User Profile button
  • Click button Continue in Safe Mode
  • Open the file causing the crash and test whether the problem is gone

Currently the issue on the 18.04 partition is related to the automatic saving of the file. I have resorted to a separate physical timer. Yet to test this same file on the 20.04 partition.

Win10, Ryzen 3900X, Libre 6.4.7.2, opening Calc file, file crashes, Turned off auto-save, problem gone. Problem does not happen on Win10 Intel i4960 notebook.

Win10, Ryzen 3900X, Libre 6.4.7.2, opening Calc file, file crashes, Turned off auto-save, problem gone. Problem does not happen on Win10 Intel i4960 notebook. Info gained from jspreadsheet answer.