feat(performance): improving implementation for better performances on big datasets

src/lerobot/datasets/dataset_metadata.py

@@ -205,11 +205,12 @@ class LeRobotDatasetMetadata:
             List of sorted episode indices that satisfy the predicate.
         """
         self.ensure_readable()
-        ep_table = self.episodes
         if candidates is not None:
             candidate_set = set(candidates)
-            ep_table = ep_table.filter(lambda ep: ep["episode_index"] in candidate_set)
-        filtered = ep_table.filter(predicate)
+            combined = lambda ep: ep["episode_index"] in candidate_set and predicate(ep)  # noqa: E731
+        else:
+            combined = predicate
+        filtered = self.episodes.filter(combined, keep_in_memory=True, load_from_cache_file=False)
         return sorted(int(idx) for idx in filtered["episode_index"])
 
     def _pull_from_repo(