gh-109653: Improve import time of importlib.metadata / email.utils

Lib/email/_parseaddr.py

@@ -13,7 +13,7 @@
     'quote',
     ]
 
-import time, calendar
+import time
 
 SPACE = ' '
 EMPTYSTRING = ''
@@ -194,6 +194,9 @@ def mktime_tz(data):
         # No zone info, so localtime is better assumption than GMT
         return time.mktime(data[:8] + (-1,))
     else:
+        # Delay the import, since mktime_tz is rarely used
+        import calendar
+
         t = calendar.timegm(data)
         return t - data[9]
 

Lib/importlib/metadata/__init__.py

@@ -1,7 +1,6 @@
 import os
 import re
 import abc
-import csv
 import sys
 import json
 import email
@@ -478,6 +477,10 @@ def make_file(name, hash=None, size_str=None):
 
         @pass_none
         def make_files(lines):
+            # Delay csv import, since Distribution.files is not as widely used
+            # as other parts of importlib.metadata
+            import csv
+
             return starmap(make_file, csv.reader(lines))
 
         @pass_none

Misc/NEWS.d/next/Library/2024-01-28-00-48-12.gh-issue-109653.vF4exe.rst

@@ -0,0 +1 @@
+Improve import time of :mod:`importlib.metadata` and :mod:`email.utils`.