I found out what was wrong with your file. It took a while to figure it out…
In this part of the document is a date field:
That 10.7.24 field is supposed to be a single field, but it’s actually 164,560 copies of the field on top of each other. Reducing that to one copy fixes the problem. Here’s a copy of the file:
I don’t know how you managed to get 164,559 extra copies of the field onto the page.
The file is still a demanding one, taking over 3 GB of memory to get it to open. But at least it opens now, before it was using 300 GB of memory, and then locking up the system.