diff --git a/hg b/hg
--- a/hg
+++ b/hg
@@ -8,16 +8,7 @@
 # This software may be used and distributed according to the terms
 # of the GNU General Public License, incorporated herein by reference.
 
-# the psyco compiler makes commits a bit faster
-# and makes changegroup merge about 20 times slower!
-# try:
-#    import psyco
-#    psyco.full()
-# except:
-#    pass
-
-import sys
 from mercurial import commands
 
-sys.exit(commands.dispatch(sys.argv[1:]))
+commands.run()
 
diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -1,4 +1,11 @@
-import os, re, traceback, sys, signal, time, mdiff
+# commands.py - command processing for mercurial
+#
+# Copyright 2005 Matt Mackall <mpm@selenic.com>
+#
+# This software may be used and distributed according to the terms
+# of the GNU General Public License, incorporated herein by reference.
+
+import os, re, sys, signal, time, mdiff
 from mercurial import fancyopts, ui, hg
 
 class UnknownCommand(Exception): pass
@@ -522,6 +529,9 @@ class SignalInterrupt(Exception): pass
 def catchterm(*args):
     raise SignalInterrupt
 
+def run():
+    sys.exit(dispatch(sys.argv[1:]))
+
 def dispatch(args):
     options = {}
     opts = [('v', 'verbose', None, 'verbose'),
@@ -562,6 +572,7 @@ def dispatch(args):
     except KeyboardInterrupt:
         u.warn("interrupted!\n")
     except TypeError, inst:
+        import traceback
         # was this an argument error?
         tb = traceback.extract_tb(sys.exc_info()[2])
         if len(tb) > 2: # no
diff --git a/mercurial/hg.py b/mercurial/hg.py
--- a/mercurial/hg.py
+++ b/mercurial/hg.py
@@ -5,9 +5,8 @@
 # This software may be used and distributed according to the terms
 # of the GNU General Public License, incorporated herein by reference.
 
-import sys, struct, sha, socket, os, time, re, urllib2, tempfile
-import urllib
-from mercurial import byterange, lock
+import sys, struct, os
+from mercurial import lock
 from mercurial.transaction import *
 from mercurial.revlog import *
 from difflib import SequenceMatcher
@@ -139,6 +138,7 @@ class changelog(revlog):
 
     def add(self, manifest, list, desc, transaction, p1=None, p2=None,
                   user=None, date=None):
+        import socket, time
         user = (user or
                 os.environ.get("HGUSER") or
                 os.environ.get("EMAIL") or
@@ -315,6 +315,7 @@ class localrepository:
             self.dirstate = dirstate(self.opener, ui, self.root)
 
     def ignore(self, f):
+        import re
         if self.ignorelist is None:
             self.ignorelist = []
             try:
@@ -966,6 +967,8 @@ class localrepository:
 
     def merge3(self, fn, my, other):
         """perform a 3-way merge in the working directory"""
+
+        import tempfile
         
         def temp(prefix, node):
             pre = "%s~%s." % (os.path.basename(fn), prefix)
@@ -1177,10 +1180,14 @@ class remoterepository:
 
 def repository(ui, path=None, create=0):
     if path and path[:7] == "http://":
+        import urllib, urllib2
         return remoterepository(ui, path)
     if path and path[:5] == "hg://":
+        import urllib, urllib2
         return remoterepository(ui, path.replace("hg://", "http://"))
     if path and path[:11] == "old-http://":
+        import urllib, urllib2
+        from mercurial import byterange
         return localrepository(ui, path.replace("old-http://", "http://"))
     else:
         return localrepository(ui, path, create)
diff --git a/mercurial/mdiff.py b/mercurial/mdiff.py
--- a/mercurial/mdiff.py
+++ b/mercurial/mdiff.py
@@ -5,7 +5,7 @@
 # This software may be used and distributed according to the terms
 # of the GNU General Public License, incorporated herein by reference.
 
-import difflib, struct, mmap
+import difflib, struct
 from mercurial.mpatch import *
 
 def unidiff(a, ad, b, bd, fn):
diff --git a/mercurial/ui.py b/mercurial/ui.py
--- a/mercurial/ui.py
+++ b/mercurial/ui.py
@@ -5,7 +5,7 @@
 # This software may be used and distributed according to the terms
 # of the GNU General Public License, incorporated herein by reference.
 
-import os, tempfile, sys, re
+import os, sys, re
 
 class ui:
     def __init__(self, verbose=False, debug=False, quiet=False,
@@ -37,6 +37,7 @@ class ui:
     def debug(self, *msg):
         if self.debugflag: self.write(*msg)
     def edit(self, text):
+        import tempfile
         (fd, name) = tempfile.mkstemp("hg")
         f = os.fdopen(fd, "w")
         f.write(text)