Woo—things are not improving with this file. It jumped in one File…Save operation to double it's size from 624 MB to 1.35 GB.
Ok, so, at least I can rescue the thing by File…New, then Layer import, don't forget to check Import Layer Objects, right>
Did that, to find not all the layer objects came over, missing things from many layers.
Huge bummer.
I'm thinking to go back several backups and re-build from there.