More deferred imports to save ~20ms

CHANGELOG.md

@@ -68,7 +68,7 @@ The table below shows which release corresponds to each branch, and what date th
 - [#1893][1893] Fix bytes warning in "pwn cyclic"
 - [#1903][1903] Add zsh completion script
 - [#1904][1904] Add bash completion script
-- [#1906][1906] Defer import of urlrequests and urllib
+- [#1906][1906] Defer import of several modules to save on startup time
 
 [1733]: https://github.com/Gallopsled/pwntools/pull/1733
 [1876]: https://github.com/Gallopsled/pwntools/pull/1876

pwnlib/tubes/remote.py

@@ -3,7 +3,6 @@
 
 import socket
 import socks
-import ssl as _ssl
 
 from pwnlib.log import getLogger
 from pwnlib.timeout import Timeout
@@ -85,6 +84,9 @@ def __init__(self, host, port,
             self.lhost, self.lport = self.sock.getsockname()[:2]
 
             if ssl:
+                # Deferred import to save startup time
+                import ssl as _ssl
+
                 ssl_args = ssl_args or {}
                 ssl_context = ssl_context or _ssl.SSLContext(_ssl.PROTOCOL_TLSv1_2)
                 if isinstance(sni, str):

pwnlib/update.py

@@ -27,8 +27,6 @@
 import os
 import time
 
-from six.moves.xmlrpc_client import ServerProxy
-
 import packaging.version
 
 from pwnlib.args import args
@@ -75,6 +73,9 @@ def available_on_pypi(prerelease=current_version.is_prerelease):
     >>> available_on_pypi(prerelease=False).is_prerelease
     False
     """
+    # Deferred import to save startup time
+    from six.moves.xmlrpc_client import ServerProxy
+
     versions = getattr(available_on_pypi, 'cached', None)
     if versions is None:
         client = ServerProxy('https://pypi.python.org/pypi')