Troubles importing from AutoCAD 2013

An old friend from me is an interior designer.
He is until now with AutoCAD 2013 on an ancient desktop computer with Windows XP
with 4 GB RAM, but Windows XP can use only 3 GB of them.

To test the possibility to move to a new system with Linux,
he sent me one of his DWG files.

I installed on my laptop, Ubuntu 20.04.1 16 GB RAM, 24 GB swap file
LibreCAD 2.1,3
 
Trying to open this, strange things happened.
System monitor showed RAM usage going up from 10 GB to 13,5 GB
(this is nearly maximum, because 2 GB is graphic card memory)
swap file usage was going up from 50 MB to 10 GB,
suddenly swap file usage was going beyond 20 GB,
at this point, I killed the process.

So why has this file such a strange behavior in LibreCAD?

2010_BAR_DESIGN.dwg

DWG  support is to be considered as experimental and rudimentary in LibreCAD.
I converted the file to dxf in an external converter (teigha file converter). It opened then, but most hatches were lost.
So if your friend moves to LibreCAD, he has to expect his existing AutoCAD drawings not to work out of the box.
The file as dxf: 2010_BAR_DESIGN.zip