Strange CPU usage of model after delete and undo

[SBor]

Hi *,

my model is getting big....and...sloooowwwww.
So, I started to debug why it is slow. I discovered one part of the model that when it is deleted it reduces the CPU time needed from 20s to 7s.
Interesting part: after undoing the deletion, the 7s stays. So what am I doing wrong - or is this a bug maybe?

I would love to share the FCStd files, but they are a bit over 2MB, which is too large for the Forum. While trying to isolate my problem I have deleted most of the content of that model but the saved files do not appear to become smaller. Is there some hidden command to purge deleted data?

ZIP is here: https://filehorst.de/d/edDDfuAk

1) unpack
2) load FelderBlock.FCStd
3) change a free cell in FelderBlock spreadsheet => 20s computation
4) select FelderBlock/FrontPart/PanelBody2gl
5) press delete key
6) change a free cell in FelderBlock spreadsheet => 7s computation
7) do undo twice for (6) and (5), PanelBody2gl is there again
8) change a free cell in FelderBlock spreadsheet => 7s computation

After saving and reopening, I am back at 20s. Strange.


OS: Windows 7 Version 6.1 (Build 7601: SP 1)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.24267 +99 (Git)
Build type: Release
Branch: Branch_0.19.3
Hash: 6530e364184ce05ccff39501e175cf2237e6ee4b
Python version: 3.8.6+
Qt version: 5.15.2
Coin version: 4.0.1
OCC version: 7.5.3
Locale: German/Germany (de_DE)