gh-156774: Scope pdb change down to the asyncio import only

Drop the other lazy imports and the lifted function-level imports, leaving just the asyncio deferral and the _get_asyncio_task() guard. Those two carry most of the win and keep the diff to five lines. import pdb -28.8% (was -42.1% with the full set) breakpoint() -> cont -28.5% python -m pdb script -26.0% pdb post-mortem -24.6%
hugovk · Sep 8, 2026 · Sep 1, 2026 · Sep 1, 2026 · Sep 1, 2026 · Sep 2, 2026
commit 89fccc3c5ec5047a0a9f7d1aa16883cb7958c5ff
@@ -73,32 +73,28 @@
 import bdb
 import dis
 import code
-lazy import glob
-lazy import json
+import glob
+import json
 import stat
-lazy import runpy
-lazy import shlex
-lazy import pydoc
 import token
 import types
 import atexit
 import codeop
-lazy import pprint
-lazy import signal
-lazy import socket
+import pprint
+import signal
+import socket
 import typing
 lazy import asyncio
 import inspect
 import weakref
-lazy import argparse
 import builtins
-lazy import tempfile
+import tempfile
 import textwrap
 import tokenize
 import itertools
 import traceback
 import linecache
-lazy import selectors
+import selectors
 import threading
 import _colorize
 
@@ -250,6 +246,7 @@ class _ModuleTarget(_ExecutableTarget):
     def __init__(self, target):
         self._target = target
 
+        import runpy
         try:
             _, self._spec, self._code = runpy._get_module_details(self._target)
         except ImportError as e:
@@ -284,6 +281,8 @@ def namespace(self):
 
 class _ZipTarget(_ExecutableTarget):
     def __init__(self, target):
+        import runpy
+
         self._target = os.path.realpath(target)
         sys.path.insert(0, self._target)
         try:
@@ -2089,6 +2088,7 @@ def do_run(self, arg):
                        'e.g. "python -m pdb myscript.py"')
             return
         if arg:
+            import shlex
             argv0 = sys.argv[0:1]
             try:
                 sys.argv = shlex.split(arg)
@@ -3743,6 +3743,7 @@ def test():
 
 # print help
 def help():
+    import pydoc
     pydoc.pager(__doc__)
 
 _usage = """\
@@ -3783,6 +3784,8 @@ def parse_args():
     # "python -m pdb -m foo -m bar" should pass "-m bar" to "foo".
     # This require some customized parsing logic to find the actual debug target.
 
+    import argparse
+
     parser = argparse.ArgumentParser(
         usage="%(prog)s [-h] [-c command] (-m module | -p pid | pyfile) [args ...]",
         description=_usage,

diff --git a/Misc/NEWS.d/next/Library/2026-08-31-11-40-00.gh-issue-156774.Pd8Lz1.rst b/Misc/NEWS.d/next/Library/2026-08-31-11-40-00.gh-issue-156774.Pd8Lz1.rst
@@ -1,2 +1,3 @@
-Speed up :mod:`pdb` startup by about 40% using :keyword:`lazy import`, and by
-skipping the :mod:`asyncio` import when no event loop has been used.
+Speed up :mod:`pdb` startup by deferring the :mod:`asyncio` import, and by
+skipping it entirely in ``Pdb._get_asyncio_task()`` when no event loop has
+been used.