Hotlink modules are instances.
I have no idea how they work memory wise, but I assume the details of the module are only loaded once to a file.
The only downside I see with them is they need to be edited in a separate Archicad.
You don't have an original 'module' stashed away somewhere in the file that you can edit directly (some call it in-line editing) - it needs to be saved as a .MOD file.
But is that really a problem?
Having a module file saved means you can add that to any job, not just the one you are working on.
I used to have curved kitchen cabinets or basic bathroom layouts that I would bring in as a module, break the link and carry on working with them.
No more having to re-create all the individual elements each time I wanted something similar.
One of the forum moderators.
Versions 6.5 to 25
Dell XPS- i7-6700 @ 3.4Ghz, 16GB ram, GeForce GTX 960 (2GB), Windows 10
Dell Precision 3510 - i7 6820HQ @ 2.70GHz, 16GB RAM, AMD FirePro W5130M, Windows 10