diff --git a/.jules/bolt.md b/.jules/bolt.md
index 5006a2b..da05510 100644
--- a/.jules/bolt.md
+++ b/.jules/bolt.md
@@ -47,3 +47,7 @@
 ## 2026-01-28 - [Avoid ThreadPoolExecutor Overhead]
 **Learning:** `ThreadPoolExecutor` context management and thread creation overhead is non-negligible for single-item or very small workloads. If a parallelizable task only has 1 unit of work (e.g., 1 batch), running it synchronously in the main thread is faster and uses less memory than spinning up a pool.
 **Action:** Check the size of the workload before creating a `ThreadPoolExecutor`. If `len(tasks) == 1`, bypass the executor and run directly.
+
+## 2024-05-24 - [Skip Validation for Known Data]
+**Learning:** Performing expensive validation (e.g. regex) on data that is already known to be valid (e.g. exists in trusted remote state) is redundant. Checking existence in a local set (O(1)) before validation avoids CPU overhead for duplicates.
+**Action:** In filtering loops, check "is already processed/known" before "is valid", especially if "valid" implies "safe to process" and "known" implies "already processed".
diff --git a/main.py b/main.py
index fcbea45..4f91e91 100644
--- a/main.py
+++ b/main.py
@@ -1121,6 +1121,10 @@ def push_rules(
     skipped_unsafe = 0
 
     for h in unique_hostnames:
+        # Optimization: Check existence first to skip regex validation for known rules
+        if h in existing_rules:
+            continue
+
         if not is_valid_rule(h):
             log.warning(
                 f"Skipping unsafe rule in {sanitize_for_log(folder_name)}: {sanitize_for_log(h)}"
@@ -1128,8 +1132,7 @@ def push_rules(
             skipped_unsafe += 1
             continue
 
-        if h not in existing_rules:
-            filtered_hostnames.append(h)
+        filtered_hostnames.append(h)
 
     if skipped_unsafe > 0:
         log.warning(
diff --git a/tests/test_push_rules_perf.py b/tests/test_push_rules_perf.py
index 421368a..63a89c8 100644
--- a/tests/test_push_rules_perf.py
+++ b/tests/test_push_rules_perf.py
@@ -98,5 +98,31 @@ def test_push_rules_multi_batch(self, mock_executor, mock_as_completed):
         # This should ALWAYS be True
         self.assertTrue(mock_executor.called, "ThreadPoolExecutor should be called for multi-batch")
 
+    @patch("main.is_valid_rule")
+    def test_push_rules_skips_validation_for_existing(self, mock_is_valid):
+        """
+        Test that is_valid_rule is NOT called for rules that are already in existing_rules.
+        """
+        mock_is_valid.return_value = True
+        hostnames = ["h1", "h2"]
+        # h1 is already known, h2 is new
+        existing_rules = {"h1"}
+
+        main.push_rules(
+            self.profile_id,
+            self.folder_name,
+            self.folder_id,
+            self.do,
+            self.status,
+            hostnames,
+            existing_rules,
+            self.client
+        )
+
+        # h1 is in existing_rules, so we should skip validation for it.
+        # h2 is NOT in existing_rules, so we should validate it.
+        # So is_valid_rule should be called EXACTLY once, with "h2".
+        mock_is_valid.assert_called_once_with("h2")
+
 if __name__ == '__main__':
     unittest.main()