diff --git a/swh/loader/core/loader.py b/swh/loader/core/loader.py
--- a/swh/loader/core/loader.py
+++ b/swh/loader/core/loader.py
@@ -411,23 +411,22 @@
             self.save_data()
 
         if self.has_contents():
-            contents = []
-            skipped_contents = []
             for obj in self.get_contents():
                 if isinstance(obj, Content):
-                    contents.append(obj)
+                    self.storage.content_add([obj])
                 elif isinstance(obj, SkippedContent):
-                    skipped_contents.append(obj)
+                    self.storage.skipped_content_add([obj])
                 else:
                     raise TypeError(f"Unexpected content type: {obj}")
-            self.storage.skipped_content_add(skipped_contents)
-            self.storage.content_add(contents)
         if self.has_directories():
-            self.storage.directory_add(list(self.get_directories()))
+            for directory in self.get_directories():
+                self.storage.directory_add([directory])
         if self.has_revisions():
-            self.storage.revision_add(list(self.get_revisions()))
+            for revision in self.get_revisions():
+                self.storage.revision_add([revision])
         if self.has_releases():
-            self.storage.release_add(list(self.get_releases()))
+            for release in self.get_releases():
+                self.storage.release_add([release])
         snapshot = self.get_snapshot()
         self.storage.snapshot_add([snapshot])
         self.flush()