diff --git a/fluent.syntax/fluent/syntax/ast.py b/fluent.syntax/fluent/syntax/ast.py
index 7ecd1826..60670c79 100644
--- a/fluent.syntax/fluent/syntax/ast.py
+++ b/fluent.syntax/fluent/syntax/ast.py
@@ -3,6 +3,36 @@
 import json
 
 
+class Visitor(object):
+    '''Read-only visitor pattern.
+
+    Subclass this to gather information from an AST.
+    To generally define which nodes not to descend in to, overload
+    `generic_visit`.
+    To handle specific node types, add methods like `visit_Pattern`.
+    The boolean value of the returned value determines if the visitor
+    descends into the children of the given AST node.
+    '''
+    def visit(self, value):
+        if isinstance(value, BaseNode):
+            self.visit_node(value)
+        if isinstance(value, list):
+            for node in value:
+                self.visit(node)
+
+    def visit_node(self, node):
+        nodename = type(node).__name__
+        visit = getattr(self, 'visit_{}'.format(nodename), self.generic_visit)
+        should_descend = visit(node)
+        if not should_descend:
+            return
+        for propname, propvalue in vars(node).items():
+            self.visit(propvalue)
+
+    def generic_visit(self, node):
+        return True
+
+
 def to_json(value, fn=None):
     if isinstance(value, BaseNode):
         return value.to_json(fn)
diff --git a/fluent.syntax/tests/syntax/fixtures_perf/workload-low.ftl b/fluent.syntax/tests/syntax/fixtures_perf/workload-low.ftl
new file mode 100644
index 00000000..8ad46ee8
--- /dev/null
+++ b/fluent.syntax/tests/syntax/fixtures_perf/workload-low.ftl
@@ -0,0 +1,378 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+# browser/locales/en-US/browser/menubar.ftl
+
+## File menu
+
+file-menu =
+    .label     = File
+    .accesskey = F
+tab-menuitem =
+    .label = New Tab
+    .accesskey = T
+tab-key =
+    .key = t
+new-user-context-menu =
+    .label = New Container Tab
+    .accesskey = C
+new-navigator-menuitem =
+    .label = New Window
+    .accesskey = N
+new-navigator-key =
+    .key = N
+new-private-window-menuitem =
+    .label = New Private Window
+    .accesskey = W
+new-non-remote-window-menuitem =
+    .label = New Non-e10s Window
+
+# Only displayed on OS X, and only on windows that aren't main browser windows,
+# or when there are no windows but Firefox is still running.
+open-location-menuitem =
+    .label = Open Location…
+open-file-menuitem =
+    .label = Open File…
+    .accesskey = O
+open-file-key =
+    .key = o
+
+close-menuitem =
+    .label = Close
+    .accesskey = C
+close-key =
+    .key = W
+close-window-menuitem =
+    .label = Close Window
+    .accesskey = d
+
+# [accesskey2] is for content area context menu
+save-page-menuitem =
+    .label = Save Page As…
+    .accesskey = A
+    .accesskey2 = P
+save-page-key =
+    .key = s
+
+email-page-menuitem =
+    .label = Email Link…
+    .accesskey = E
+
+print-setup-menuitem =
+    .label = Page Setup…
+    .accesskey = u
+print-preview-menuitem =
+    .label = Print Preview…
+    .accesskey = v
+print-menuitem =
+    .label = Print…
+    .accesskey = P
+print-key =
+    .key = p
+
+go-offline-menuitem =
+    .label = Work Offline
+    .accesskey = k
+
+quit-application-menuitem =
+    .label = Quit
+    .accesskey = Q
+quit-application-menuitem-win =
+    .label = Exit
+    .accesskey = x
+quit-application-menuitem-mac =
+    .label = Quit { -brand-shorter-name }
+# Used by both Linux and OSX builds
+quit-application-key-unix =
+    .key = Q
+
+## Edit menu
+
+edit-menu =
+    .label = Edit
+    .accesskey = E
+undo-menuitem =
+    .label = Undo
+    .accesskey = U
+undo-key =
+    .key = Z
+redo-menuitem =
+    .label = Redo
+    .accesskey = R
+redo-key =
+    .key = Y
+cut-menuitem =
+    .label = Cut
+    .accesskey = t
+cut-key =
+    .key = X
+copy-menuitem =
+    .label = Copy
+    .accesskey = C
+copy-key =
+    .key = C
+paste-menuitem =
+    .label = Paste
+    .accesskey = P
+paste-key =
+    .key = V
+delete-menuitem =
+    .label = Delete
+    .accesskey = D
+delete-key =
+    .key = D
+select-all-menuitem =
+    .label = Select All
+    .accesskey = A
+select-all-key =
+    .key = A
+
+find-on-menuitem =
+    .label = Find in This Page…
+    .accesskey = F
+find-on-key =
+    .key = f
+find-again-menuitem =
+    .label = Find Again
+    .accesskey = g
+find-again-key1 =
+    .key = g
+find-again-key2 =
+    .keycode = VK_F3
+find-selection-key =
+    .key = e
+
+bidi-switch-text-direction-menuitem =
+    .label = Switch Text Direction
+    .accesskey = w
+bidi-switch-text-direction-key =
+    .key = X
+
+preferences-menuitem =
+    .label = Options
+    .accesskey = O
+preferences-menuitem-unix =
+    .label = Preferences
+    .accesskey = n
+
+
+## View menu
+
+view-menu =
+    .label = View
+    .accesskey = V
+view-toolbars-menu =
+    .label = Toolbars
+    .accesskey = T
+view-sidebar-menu =
+    .label = Sidebar
+    .accesskey = e
+view-customize-toolbar-menuitem =
+    .label = Customize…
+    .accesskey = C
+
+full-zoom-menu =
+    .label = Zoom
+    .accesskey = Z
+full-zoom-enlarge-menuitem =
+    .label = Zoom In
+    .accesskey = I
+full-zoom-enlarge-key1 =
+    .key = +
+full-zoom-enlarge-key2 =
+    .key = {""}
+full-zoom-enlarge-key3 =
+    .key = {""}
+full-zoom-reduce-menuitem =
+    .label = Zoom Out
+    .accesskey = O
+full-zoom-reduce-key1 =
+    .key = -
+full-zoom-reduce-key2 =
+    .key = {""}
+full-zoom-reset-menuitem =
+    .label = Reset
+    .accesskey = R
+full-zoom-reset-key1 =
+    .key = 0
+full-zoom-reset-key2 =
+    .key = {""}
+full-zoom-toggle-menuitem =
+    .label = Zoom Text Only
+    .accesskey = T
+
+page-style-menu =
+    .label = Page Style
+    .accesskey = y
+page-style-no-style-menuitem =
+    .label = No Style
+    .accesskey = n
+page-style-persistent-only-menuitem =
+    .label = Basic Page Style
+    .accesskey = b
+
+show-all-tabs-menuitem =
+    .label = Show All Tabs
+    .accesskey = A
+bidi-switch-page-direction-menuitem =
+    .label = Switch Page Direction
+    .accesskey = D
+
+## Full Screen controls
+## Match what Safari and other Apple applications use on OS X Lion.
+
+enter-full-screen-menuitem =
+    .label = Enter Full Screen
+    .accesskey = F
+exit-full-screen-menuitem =
+    .label = Exit Full Screen
+    .accesskey = F
+full-screen-menuitem =
+    .label = Full Screen
+    .accesskey = F
+full-screen-key =
+    .key = f
+
+
+## History menu
+
+history-menu =
+    .label = History
+    .accesskey = s
+show-all-history-menuitem =
+    .label = Show All History
+show-all-history-key =
+    .key = H
+clear-recent-history-menuitem =
+    .label = Clean Recent History…
+history-synced-tabs-menuitem =
+    .label = Synced Tabs
+history-restore-last-session-menuitem =
+    .label = Restore Previous Session
+history-undo-menu =
+    .label = Recently Closed Tabs
+history-undo-window-menu =
+    .label = Recently Closed Windows
+
+
+## Bookmarks menu
+
+bookmarks-menu =
+    .label = Bookmarks
+    .accesskey = B
+show-all-bookmarks-menuitem =
+    .label = Show All Bookmarks
+show-all-bookmarks-key =
+    .key = b
+# The "key" attribute should not contain the letters A-F since the are reserved
+# shortcut keys on Linux.
+show-all-bookmarks-key-gtk =
+    .key = o
+bookmark-this-page-broadcaster =
+    .label = Bookmark This Page
+edit-this-page-broadcaster =
+    .label = Edit This Page
+bookmark-this-page-key =
+    .key = d
+subscribe-to-page-menuitem =
+    .label = Subscribe to This Page…
+subscribe-to-page-menupopup =
+    .label = Subscribe to This Page…
+add-cur-pages-menuitem =
+    .label = Bookmark All Tabs…
+recent-bookmarks-menuitem =
+    .label = Recently Bookmarked
+
+other-bookmarks-menu =
+    .label = Other Bookmarks
+personalbar-menu =
+    .label = Bookmarks Toolbar
+    .accesskey = B
+
+
+## Tools menu
+
+tools-menu =
+    .label = Tools
+    .accesskey = T
+downloads-menuitem =
+    .label = Downloads
+    .accesskey = D
+downloads-key =
+    .key = j
+downloads-key-unix =
+    .key = y
+addons-menuitem =
+    .label = Add-ons
+    .accesskey = A
+addons-key =
+    .key = A
+
+sync-sign-in-menuitem =
+    .label = Sign In To { sync-brand-short-name }…
+    .accesskey = Y
+sync-sync-now-menuitem =
+    .label = Sync Now
+    .accesskey = S
+sync-re-auth-menuitem =
+    .label = Reconnect to { sync-brand-short-name }…
+    .accesskey = R
+sync-toolbar-button =
+    .label = Sync
+
+web-developer-menu =
+    .label = Web Developer
+    .accesskey = W
+
+page-source-broadcaster =
+    .label = Page Source
+    .accesskey = o
+page-source-key =
+    .key = u
+page-info-menuitem =
+    .label = Page Info
+    .accesskey = I
+page-info-key =
+    .key = i
+mirror-tab-menu =
+    .label = Mirror Tab
+    .accesskey = m
+
+
+# browser/locales/en-US/browser/toolbar.ftl
+
+urlbar-textbox =
+    .placeholder = Search or enter address
+    .accesskey = d
+
+
+## Toolbar items
+
+view-bookmarks-broadcaster =
+    .label = Bookmarks
+view-bookmarks-key =
+    .key = b
+view-bookmarks-key-win =
+    .key = i
+
+view-history-broadcaster =
+    .label = History
+view-history-key =
+    .key = h
+view-tabs-broadcaster =
+    .label = Synced Tabs
+
+
+# browser/branding/official/locales/en-US/brand.ftl
+
+-brand-shorter-name    = Firefox
+-brand-short-name      = Firefox
+-brand-full-name       = Mozilla Firefox
+vendor-short-name     = Mozilla
+
+trademark-info        = 
+    Firefox and the Firefox logos are trademarks of the Mozilla Foundation.
+
+sync-brand-short-name = Sync
diff --git a/fluent.syntax/tests/syntax/test_visitor.py b/fluent.syntax/tests/syntax/test_visitor.py
new file mode 100644
index 00000000..c9c313dc
--- /dev/null
+++ b/fluent.syntax/tests/syntax/test_visitor.py
@@ -0,0 +1,116 @@
+from __future__ import unicode_literals
+
+import codecs
+from collections import defaultdict
+import os
+import unittest
+import timeit
+
+from fluent.syntax.parser import FluentParser
+from fluent.syntax import ast
+from tests.syntax import dedent_ftl
+
+
+class MockVisitor(ast.Visitor):
+    def __init__(self):
+        self.calls = defaultdict(int)
+        self.pattern_calls = 0
+
+    def generic_visit(self, node):
+        self.calls[type(node).__name__] += 1
+        return super(MockVisitor, self).generic_visit(node)
+
+    def visit_Pattern(self, node):
+        self.pattern_calls += 1
+        return False
+
+
+class TestVisitor(unittest.TestCase):
+    def test_resource(self):
+        resource = FluentParser().parse(dedent_ftl('''\
+        one = Message
+        # Comment
+        two = Messages
+        three = Messages with
+            .an = Attribute
+        '''))
+        mv = MockVisitor()
+        mv.visit(resource)
+        self.assertEqual(mv.pattern_calls, 4)
+        self.assertDictEqual(
+            mv.calls,
+            {
+                'Resource': 1,
+                'Comment': 1,
+                'Message': 3,
+                'Identifier': 4,
+                'Attribute': 1,
+                'Span': 10,
+            }
+        )
+
+
+class WordCounter(object):
+    def __init__(self):
+        self.word_count = 0
+    def __call__(self, node):
+        if isinstance(node, ast.TextElement):
+            self.word_count += len(node.value.split())
+        return node
+
+class VisitorCounter(ast.Visitor):
+    def __init__(self):
+        self.word_count = 0
+
+    def generic_visit(self, node):
+        return not isinstance(node, (ast.Span, ast.Annotation))
+
+    def visit_TextElement(self, node):
+        self.word_count += len(node.value.split())
+        return False
+
+
+class TestPerf(unittest.TestCase):
+    def setUp(self):
+        parser = FluentParser()
+        workload = os.path.join(
+            os.path.dirname(__file__), 'fixtures_perf', 'workload-low.ftl'
+        )
+        with codecs.open(workload, encoding='utf-8') as f:
+            self.resource = parser.parse(f.read())
+
+    def test_traverse(self):
+        counter = WordCounter()
+        self.resource.traverse(counter)
+        self.assertEqual(counter.word_count, 277)
+
+    def test_visitor(self):
+        counter = VisitorCounter()
+        counter.visit(self.resource)
+        self.assertEqual(counter.word_count, 277)
+
+
+def gather_stats(method, repeat=10, number=50):
+    t = timeit.Timer(
+        setup='''
+from tests.syntax import test_visitor
+test = test_visitor.TestPerf('test_{}')
+test.setUp()
+'''.format(method),
+        stmt='test.test_{}()'.format(method)
+    )
+    return [
+        result/number for result in
+        t.repeat(repeat=repeat, number=number)
+    ]
+
+
+
+if __name__=='__main__':
+    for m in ('traverse', 'visitor'):
+        results = gather_stats(m)
+        try:
+            import statistics
+            print("{}:\t{}".format(m, statistics.mean(results)))
+        except ImportError:
+            print("{}:\t{}".format(m, sum(results)/len(results)))