Slow block update - Rhino 7

I have a model - call it ParentFile - that has several blocks within it - some embedded, some embedded and linked. Some of these blocks have blocks in them, mostly just embedded - let’s call them ChildFiles.
The ParentFile is about 31Mb.
I insert this ParentFile in another file - call it GrandFile, embedded and linked. The resulting file is similarly sized. On the GrandFile, I have a few layouts and ClippingPlanes.

I then update something on when I update one of the linked ChildFiles, I can quickly update the ParentFile. But then, on GrandFile you can see that both the ChildFile and ParentFile are newer. Updating the Child is quick but updating the Parent takes 30 to 60 minutes.

Any idea what is going on here?

Hi @nsgma ,
We need a set of files to test this with.
We also need your SystemInfo. Open Rhino type SystemInfo and paste the text results here.

Zip them and upload here.
Add this link to your upload.
Slow block update - Rhino 7

Thank you.
This will help us to see the issue here.
Mary Ann Fugier