diff --git a/src/bioetl/infrastructure/adapters/common/deduplication.py b/src/bioetl/infrastructure/adapters/common/deduplication.py
index 18e1a8f9b9..e6dd308fb5 100644
--- a/src/bioetl/infrastructure/adapters/common/deduplication.py
+++ b/src/bioetl/infrastructure/adapters/common/deduplication.py
@@ -35,14 +35,9 @@
 
 def deduplicate_preserving_order(values: Iterable[str]) -> list[str]:
     """Return unique values while preserving the original order."""
-    unique_values: list[str] = []
-    seen_values: set[str] = set()
-    for value in values:
-        if value in seen_values:
-            continue
-        seen_values.add(value)
-        unique_values.append(value)
-    return unique_values
+    # Optimization: dict.fromkeys leverages C-level iteration and insertion order
+    # preservation to deduplicate faster than a pure-Python seen-set loop.
+    return list(dict.fromkeys(values))
 
 
 def iter_deduplicated_records(