Well, I see a number of new user mistakes that will impact performance.
You are using a “slow” style with Profiles turned on. Turn them off to reduce the graphics load.
You have the model placed at a huge distance from the origin. this can create performance problems.
It would help if you turn off Length Snapping in the Units settings.
You should learn about using groups or components for your walls. ALL of the geometry that you’ve created is loose, ungrouped geometry. This makes your model difficult to work with
Also learn about correct tag usage. ALL edges and faces should be created and remain untagged. Only groups and components should be given tags. I fixed the incorrect tag usage in your model.
Also you don’t need to be hoarding all the components you’ve tried from the 3D Warehouse. Purging unused stuff once in awhile is important to keep your file from getting bloated and reducing performance.
Another thing that will reduce performance is the excessively large texture images in the model. This is after purging the unused ones.
There also seems to be a lot of unneeded edges and faces–places where you’ve created complanar faces that aren’t needed.
Keeping your model under control is important in preventing issues such as those you report.
Also make sure you are staying on top of keeping the faces oriented correctly. There should be no blue back faces exposed in your model. If you plan to do any rendered images from the model, face orientation is critical for getting the desired results. Here with the Face Style set to Monochrome you can see the reversed faces. Best practice is to avoid applying textures until after the face orientation is correct.
If you find your computer is slowing down while working in the model, setting the face style to Monochrome.
Did you install SketchUp correctly? On Windows that requires right clicking on the downloaded installer and choosing Run as administrator. If you didn’t do that, close SketchUp, do a cold reboot of your computer, find the installer in your Downloads folder, right click on it, choose Run as administrator, and then choose Repair when prompted.
After the cleanup I did the file size has been reduced by more than 65%. There’s still nearly 13 million edges and over 7 million faces. Your model is still extremely “heavy”.
BTW, I can’t say that I’ve ever seen so many appartment dwellers all eating sushi on the same night. 
Here’s the reduced file. See if it behaves for you better.
https://www.dropbox.com/scl/fi/0m4e8nbnkz6ys2qjuscji/sketchup-flat-plan-minus-things-purged.skp?rlkey=q5nuzc88yg6zxx7kipal2t7wv&st=p0xzynm2&dl=0