Those placed views, how many elements do they include?
I've worked on a 3rd party file a while back where the project had one worksheet which contained all the detail drawings and the details had a few exploded DWG files which had a lot of duplicate element. The result was I think in the hundreds of thousands of elements on one view, which made Archicad come to a crawl, much like you described.
4 GB seems about a magnitude of 2 too big, but that is mostly scaling up from projects we have with about 50-100 layouts.
There should be a white paper floating around for 'big projects', but it is probably very outdated by now.
ArchiCAD23 and up should not be updating things that are not shown on cropped views on layouts, which should make things a bit faster.