Optimistic updates to search
In some apps, like Roam or Obsidian, when you make a note or edit the contents of the note, those changes are immediately reflected in search.
Other apps, like Notion, rely on a delayed indexing process. Because of this, there is a delay (sometimes many minutes) before changes are reflected in search.
This makes a big difference for constructing / managing knowledge graphs, making it quite irritating to do in Notion, for example.