diff --git a/models/AuditLogModel.php b/models/AuditLogModel.php
index f0eea92..dd691cc 100644
--- a/models/AuditLogModel.php
+++ b/models/AuditLogModel.php
@@ -309,17 +309,28 @@ class AuditLogModel
      * @param int $daysToKeep Number of days of logs to keep
      * @return int Number of deleted records
      */
-    public function deleteOldLogs($daysToKeep = 90)
+    public function deleteOldLogs($daysToKeep = 90, $batchSize = 1000)
     {
+        // Batched to bound how long each statement holds row locks — an
+        // unbounded single DELETE on a large backlog (e.g. the first run after
+        // enabling/changing retention, or after the cron silently missed runs)
+        // would otherwise contend with the frequent concurrent INSERTs the
+        // audit log receives from live traffic.
         $stmt = $this->conn->prepare(
-            "DELETE FROM audit_log WHERE created_at < DATE_SUB(NOW(), INTERVAL ? DAY)"
+            "DELETE FROM audit_log WHERE created_at < DATE_SUB(NOW(), INTERVAL ? DAY) ORDER BY audit_id LIMIT ?"
         );
-        $stmt->bind_param("i", $daysToKeep);
-        $stmt->execute();
-        $affectedRows = $stmt->affected_rows;
+        $stmt->bind_param("ii", $daysToKeep, $batchSize);
+
+        $totalDeleted = 0;
+        do {
+            $stmt->execute();
+            $affected = $stmt->affected_rows;
+            $totalDeleted += $affected;
+        } while ($affected > 0);
+
         $stmt->close();
 
-        return $affectedRows;
+        return $totalDeleted;
     }
 
     /**