diff --git a/guardrails/prompt/messages.py b/guardrails/prompt/messages.py
index 8740cc46c..09d79a806 100644
--- a/guardrails/prompt/messages.py
+++ b/guardrails/prompt/messages.py
@@ -61,6 +61,8 @@ def format(
     ):
         """Format the messages using the given keyword arguments."""
         formatted_messages = []
+        # Precompute the keys for all kwargs, so repeated set intersection is O(1)
+        kwargs_keys = set(kwargs.keys())
         for message in self.source:
             if isinstance(message["content"], str):
                 msg_str = message["content"]
@@ -68,7 +70,7 @@ def format(
                 msg_str = message["content"]._source
             # Only use the keyword arguments that are present in the message.
             vars = get_template_variables(msg_str)
-            filtered_kwargs = {k: v for k, v in kwargs.items() if k in vars}
+            filtered_kwargs = {k: kwargs[k] for k in vars if k in kwargs_keys}
 
             # Return another instance of the class with the formatted message.
             formatted_message = Template(msg_str).safe_substitute(**filtered_kwargs)
@@ -91,3 +93,9 @@ def substitute_constants(self, text):
             text = template.safe_substitute(**mapping)
 
         return text
+
+
+def _filtered_kwargs(kwargs, vars):
+    # Efficient set intersection for needed kwargs
+    vars_set = set(vars)
+    return {k: kwargs[k] for k in vars_set & kwargs.keys()}
diff --git a/guardrails/utils/templating_utils.py b/guardrails/utils/templating_utils.py
index 2284c6f00..a96ee80af 100644
--- a/guardrails/utils/templating_utils.py
+++ b/guardrails/utils/templating_utils.py
@@ -1,12 +1,13 @@
-import collections
 from string import Template
 from typing import List
+import re
+
+_TEMPLATE_VAR_PATTERN = re.compile(r"\${([_a-zA-Z][_a-zA-Z0-9]*)}")
 
 
 def get_template_variables(template: str) -> List[str]:
+    # If Template provides identifiers, use that (backward-compatible)
     if hasattr(Template, "get_identifiers"):
         return Template(template).get_identifiers()  # type: ignore
-    else:
-        d = collections.defaultdict(str)
-        Template(template).safe_substitute(d)
-        return list(d.keys())
+    # Fast regex extraction for variable names in the template string
+    return list({match.group(1) for match in _TEMPLATE_VAR_PATTERN.finditer(template)})