Yes, I can see why any version of TurboCAD would be struggling!
Your tower is made up of groups of groups of graphics et cetera.
I exploded this three or four times to get down to the separate elements, without the part tree stuff.
It then loads more quickly and reliably.
I would do as John suggests, but add, that the tower could be simplified to fewer elements, which would make life easier, for any CAD program.
It is also worth mentioning, that version 16, will only access < 2 GB of RAM.
I hope this helps.