I have 18100 files and have experienced problems with loading the workspace myself but never this long.
See thread:
I am beginning to think it is not a pre-1.5.8 issue (not sure about where any electron changes happened) but it cropped up before 1.5.3. as well. Hard to keep track and I cannot investigate.
The loading of the workspace does take longer when doing a fresh install but a I like to delete all things in the folder specified above (or corresponding folder on other OS) anyway once in a while (every month or so) to have faster searches.
Problem is that if I delete or rename the workspace.json file, it doesn’t seem to make a difference. Possibly the workspaces.json fle would need to be renamed (deleted) as well.
So more investigating is needed but so far I’ve been able to use Obsidian and as you can see from the lack of user responses, I am not exactly being helped by brainstorming together.
I am on Linux (not Wayland) and tried only the debian package and recently the appimage. I don’t quite remember my experience on Windows 10 now as it has been months since I last used the Windows install.
So maybe try to get a 1.4.16 installer – I think that’s still compatible with the latest 1.5.12 version (if not, the 1.5.3 one). Try renaming the workspace and workspaces files to bak or backup or sg as well.