diff --git a/importlib_metadata/__init__.py b/importlib_metadata/__init__.py
index 6dfaad0c..58bbd95e 100644
--- a/importlib_metadata/__init__.py
+++ b/importlib_metadata/__init__.py
@@ -14,7 +14,6 @@
 import email
 import functools
 import itertools
-import json
 import operator
 import os
 import pathlib
@@ -29,8 +28,6 @@
 from itertools import starmap
 from typing import Any, Iterable, List, Mapping, Match, Optional, Set, cast
 
-from zipp.compat.overlay import zipfile
-
 from . import _meta
 from ._collections import FreezableDefaultDict, Pair
 from ._compat import (
@@ -675,6 +672,9 @@ def origin(self):
         return self._load_json('direct_url.json')
 
     def _load_json(self, filename):
+        # Deferred for performance (python/importlib_metadata#503)
+        import json
+
         return pass_none(json.loads)(
             self.read_text(filename),
             object_hook=lambda data: types.SimpleNamespace(**data),
@@ -777,6 +777,8 @@ def children(self):
         return []
 
     def zip_children(self):
+        from zipp.compat.overlay import zipfile
+
         zip_path = zipfile.Path(self.root)
         names = zip_path.root.namelist()
         self.joinpath = zip_path.joinpath
diff --git a/newsfragments/503.feature.rst b/newsfragments/503.feature.rst
new file mode 100644
index 00000000..7e6bdc7a
--- /dev/null
+++ b/newsfragments/503.feature.rst
@@ -0,0 +1 @@
+Deferred import of json
\ No newline at end of file