diff --git a/oslo_utils/strutils.py b/oslo_utils/strutils.py
index 782903d..2851ced 100644
--- a/oslo_utils/strutils.py
+++ b/oslo_utils/strutils.py
@@ -58,30 +58,37 @@ _SANITIZE_KEYS = ['adminPass', 'admin_pass', 'password', 'admin_password',
 # _SANITIZE_KEYS we already have. This way, we only have to add the new key
 # to the list of _SANITIZE_KEYS and we can generate regular expressions
 # for XML and JSON automatically.
-_SANITIZE_PATTERNS_2 = []
-_SANITIZE_PATTERNS_1 = []
+_SANITIZE_PATTERNS_2 = {}
+_SANITIZE_PATTERNS_1 = {}
 
 # NOTE(amrith): Some regular expressions have only one parameter, some
 # have two parameters. Use different lists of patterns here.
 _FORMAT_PATTERNS_1 = [r'(%(key)s\s*[=]\s*)[^\s^\'^\"]+']
-_FORMAT_PATTERNS_2 = [r'(%(key)s\s*[=]\s*[\"\']).*?([\"\'])',
-                      r'(%(key)s\s+[\"\']).*?([\"\'])',
+_FORMAT_PATTERNS_2 = [r'(%(key)s\s*[=]\s*[\"\'])[^\"\']*([\"\'])',
+                      r'(%(key)s\s+[\"\'])[^\"\']*([\"\'])',
                       r'([-]{2}%(key)s\s+)[^\'^\"^=^\s]+([\s]*)',
-                      r'(<%(key)s>).*?(</%(key)s>)',
-                      r'([\"\']%(key)s[\"\']\s*:\s*[\"\']).*?([\"\'])',
-                      r'([\'"].*?%(key)s[\'"]\s*:\s*u?[\'"]).*?([\'"])',
-                      r'([\'"].*?%(key)s[\'"]\s*,\s*\'--?[A-z]+\'\s*,\s*u?'
-                      '[\'"]).*?([\'"])',
+                      r'(<%(key)s>)[^<]*(</%(key)s>)',
+                      r'([\"\']%(key)s[\"\']\s*:\s*[\"\'])[^\"\']*([\"\'])',
+                      r'([\'"][^"\']*%(key)s[\'"]\s*:\s*u?[\'"])[^\"\']*'
+                      '([\'"])',
+                      r'([\'"][^\'"]*%(key)s[\'"]\s*,\s*\'--?[A-z]+\'\s*,\s*u?'
+                      '[\'"])[^\"\']*([\'"])',
                       r'(%(key)s\s*--?[A-z]+\s*)\S+(\s*)']
 
+# NOTE(dhellmann): Keep a separate list of patterns by key so we only
+# need to apply the substitutions for keys we find using a quick "in"
+# test.
 for key in _SANITIZE_KEYS:
+    _SANITIZE_PATTERNS_1[key] = []
+    _SANITIZE_PATTERNS_2[key] = []
+
     for pattern in _FORMAT_PATTERNS_2:
         reg_ex = re.compile(pattern % {'key': key}, re.DOTALL)
-        _SANITIZE_PATTERNS_2.append(reg_ex)
+        _SANITIZE_PATTERNS_2[key].append(reg_ex)
 
     for pattern in _FORMAT_PATTERNS_1:
         reg_ex = re.compile(pattern % {'key': key}, re.DOTALL)
-        _SANITIZE_PATTERNS_1.append(reg_ex)
+        _SANITIZE_PATTERNS_1[key].append(reg_ex)
 
 
 def int_from_bool_as_string(subject):
@@ -230,19 +237,18 @@ def mask_password(message, secret="***"):
         # byte string. A better solution will be provided in Kilo.
         pass
 
+    substitute1 = r'\g<1>' + secret
+    substitute2 = r'\g<1>' + secret + r'\g<2>'
+
     # NOTE(ldbragst): Check to see if anything in message contains any key
     # specified in _SANITIZE_KEYS, if not then just return the message since
     # we don't have to mask any passwords.
-    if not any(key in message for key in _SANITIZE_KEYS):
-        return message
-
-    substitute = r'\g<1>' + secret + r'\g<2>'
-    for pattern in _SANITIZE_PATTERNS_2:
-        message = re.sub(pattern, substitute, message)
-
-    substitute = r'\g<1>' + secret
-    for pattern in _SANITIZE_PATTERNS_1:
-        message = re.sub(pattern, substitute, message)
+    for key in _SANITIZE_KEYS:
+        if key in message:
+            for pattern in _SANITIZE_PATTERNS_2[key]:
+                message = re.sub(pattern, substitute2, message)
+            for pattern in _SANITIZE_PATTERNS_1[key]:
+                message = re.sub(pattern, substitute1, message)
 
     return message
 
diff --git a/tools/perf_test_mask_password.py b/tools/perf_test_mask_password.py
new file mode 100644
index 0000000..f69a734
--- /dev/null
+++ b/tools/perf_test_mask_password.py
@@ -0,0 +1,52 @@
+#!/usr/bin/env python
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+"""Performance tests for mask_password.
+"""
+
+from __future__ import print_function
+
+import timeit
+
+from oslo_utils import strutils
+
+# A moderately sized input (~50K) string
+# http://paste.openstack.org/raw/155864/
+# infile = '155864.txt'
+
+# Untruncated version of the above (~310K)
+# http://dl.sileht.net/public/payload.json.gz
+infile = 'large_json_payload.txt'
+
+with open(infile, 'r') as f:
+    input_str = f.read()
+print('payload has %d bytes' % len(input_str))
+
+for pattern in strutils._SANITIZE_PATTERNS_2['admin_pass']:
+    print('\ntesting %s' % pattern.pattern)
+    t = timeit.Timer(
+        "re.sub(pattern, r'\g<1>***\g<2>', payload)",
+        """
+import re
+payload = '''%s'''
+pattern = re.compile(r'''%s''')
+""" % (input_str, pattern.pattern))
+    print(t.timeit(1))
+
+t = timeit.Timer(
+    "strutils.mask_password('''" + input_str + "''')",
+    "from oslo_utils import strutils",
+)
+print(t.timeit(1))