@laurent and @personalizedrefriger, tell me if there is a similar big unresolved slowness problem with the Android application, I might wait or else I will try to do without the Android app, thanks
Part of the performance issue on desktop was that it re-rendered the entire notebook and tag lists whenever a new note, notebook, or tag was added. The fix was to only render visible notebooks/tags and to rebuild the data used for this rendering less often.
This fix has not been applied to Android, but because the Android sidebar doesn't show tags, the issue might not be as significant as it was on desktop.
Please also be aware that the Android app does not have background sync — the device needs to be turned on and Joplin must be open for a sync to complete. See this GitHub issue for details.