Notion rarely gets slow because of your internet. It gets slow because of what a page is asked to render. Here's what to check, in order.
Clear the local cache
- Open the desktop app and go to Settings → Applications.
- Choose Clear local cache and confirm.
- Restart Notion and reopen the slow page.
Trim heavy database views
Gallery views with cover images and rollups are the most expensive thing Notion renders. Switch the default view to Table, hide unused properties, and add a filter so the view loads fewer rows.