diff --git a/.jules/bolt.md b/.jules/bolt.md
index 8ce7ce8f7..a5bc227c2 100644
--- a/.jules/bolt.md
+++ b/.jules/bolt.md
@@ -77,3 +77,7 @@
 ## 2024-11-20 - Optimize multiple tuple generation from a single collection
 **Learning:** `build_rule_metadata` derives exactly two collections, `owasp` and `cwe`, from the same references. Replacing its two generator traversals with one explicit loop reduces element visits from about 2N to N. Both versions remain O(N), so this is a constant-factor optimization rather than an asymptotic complexity improvement.
 **Action:** Combine repeated traversal when fixed derived collections share one source, while preserving ordering and classification semantics. Benchmark the production hot path before claiming a material wall-clock improvement.
+
+## 2024-11-20 - Optimizing string deduplication with dict.fromkeys()
+**Learning:** While `dict.fromkeys()` is excellent for string deduplication, using it with a generator expression inside incurs generator overhead.
+**Action:** When optimizing string deduplication in Python hot paths, prefer explicit `for` loops updating a local dictionary (`seen[key] = None`) over generator comprehensions passed to `dict.fromkeys()`. This avoids generator overhead while preserving element insertion order.
diff --git a/appguardrail_core/rules.py b/appguardrail_core/rules.py
index c06ea203a..84cc7d2ea 100644
--- a/appguardrail_core/rules.py
+++ b/appguardrail_core/rules.py
@@ -106,12 +106,12 @@ def as_dict(self) -> dict[str, Any]:
 
 def extract_public_references(message: str) -> tuple[str, ...]:
     """Extract OWASP, CWE, and CVE references already embedded in rule copy."""
-    return tuple(
-        dict.fromkeys(
-            " ".join(match.group(1).split())
-            for match in REFERENCE_RE.finditer(message or "")
-        )
-    )
+    # ⚡ Bolt: Use an explicit loop updating a local dict instead of dict.fromkeys()
+    # with a generator comprehension to avoid generator overhead while preserving order.
+    seen: dict[str, None] = {}
+    for match in REFERENCE_RE.finditer(message or ""):
+        seen[" ".join(match.group(1).split())] = None
+    return tuple(seen)
 
 
 def _category_for_references(references: tuple[str, ...], fallback: str) -> str:
@@ -175,7 +175,5 @@ def validate_rule_metadata(metadata: RuleMetadata | dict[str, Any]) -> list[str]
 
 def _merge_references(*groups: tuple[str, ...]) -> tuple[str, ...]:
     return tuple(
-        dict.fromkeys(
-            reference for group in groups for reference in group if reference
-        )
+        dict.fromkeys(reference for group in groups for reference in group if reference)
     )