Parallelise.

backend/infrastructure/src/video/adapter.rs

@@ -78,8 +78,18 @@ impl LibraryItemAdapter {
 
 impl VideoPort for LibraryItemAdapter {
     fn list_root_folder(&self) -> Result<Vec<LibraryRawItem>, VideoError> {
-        let file_system_items = self.get_root_folder_read_library_items()?;
-        let db_items = self.get_all_library_items_from_db()
+        let adapter1 = self.clone();
+        let file_system_handle = std::thread::spawn(move || {
+            adapter1.get_root_folder_read_library_items()
+        });
+
+        let adapter2 = self.clone();
+        let db_handle = std::thread::spawn(move || {
+            adapter2.get_all_library_items_from_db()
+        });
+
+        let file_system_items = file_system_handle.join().unwrap()?;
+        let db_items = db_handle.join().unwrap()
             .map_err(|_| VideoError::FileReadingTechnicalIssue)?;
 
         let merged = Self::merge_item_lists(file_system_items, db_items);