diff --git a/benchmarks/perf-tool/okpt/test/steps/steps.py b/benchmarks/perf-tool/okpt/test/steps/steps.py
index 9e70123c3d..7230bc1f4f 100644
--- a/benchmarks/perf-tool/okpt/test/steps/steps.py
+++ b/benchmarks/perf-tool/okpt/test/steps/steps.py
@@ -287,14 +287,14 @@ def _action(self):
         def action(doc_id):
             return {'index': {'_index': self.index_name, '_id': doc_id}}
 
-        index_responses = []
+        # Maintain minimal state outside of this loop. For large data sets, too
+        # much state may cause out of memory failure
         for i in range(0, self.doc_count, self.bulk_size):
             partition = self.dataset.read(self.bulk_size)
             if partition is None:
                 break
             body = bulk_transform(partition, self.field_name, action, i)
-            result = bulk_index(self.opensearch, self.index_name, body)
-            index_responses.append(result)
+            bulk_index(self.opensearch, self.index_name, body)
 
         self.dataset.reset()