diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1a937080..1d184a24 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Changelog
 
+## Unreleased
+
+- Fixed issue loader grouping an unordered iterable by partition, speeding up loads of items with mixed partitions [#116](https://github.com/stac-utils/pgstac/pull/116)
+
 ## [v0.6.3]
 
 ### Fixed
diff --git a/pypgstac/pypgstac/load.py b/pypgstac/pypgstac/load.py
index f61532db..589c96bb 100644
--- a/pypgstac/pypgstac/load.py
+++ b/pypgstac/pypgstac/load.py
@@ -552,7 +552,8 @@ def load_items(
             items = self.read_hydrated(file)
 
         for chunk in chunked_iterable(items, chunksize):
-            list(chunk).sort(key=lambda x: x["partition"])
+            chunk = list(chunk)
+            chunk.sort(key=lambda x: x["partition"])
             for k, g in itertools.groupby(chunk, lambda x: x["partition"]):
                 self.load_partition(self._partition_cache[k], g, insert_mode)