diff --git a/subliminal/providers/opensubtitlescom.py b/subliminal/providers/opensubtitlescom.py
index 22a60659..493ef411 100644
--- a/subliminal/providers/opensubtitlescom.py
+++ b/subliminal/providers/opensubtitlescom.py
@@ -697,7 +697,8 @@ def query(
                 )
 
                 # Some criteria are redundant, so skip duplicates
-                unique_ids = [s.id for s in subtitles]
+                # Use set for faster search
+                unique_ids = {s.id for s in subtitles}
                 if subtitle.id not in unique_ids:
                     logger.debug('Found subtitle %r', subtitle)
                     subtitles.append(subtitle)