diff -r d083b6ead156 Lib/base64.py
--- a/Lib/base64.py	Mon Mar 10 11:05:07 2014 +0100
+++ b/Lib/base64.py	Mon Mar 10 13:24:31 2014 +0200
@@ -139,7 +139,7 @@
 # Base32 encoding/decoding must be done in Python
 _b32alphabet = b'ABCDEFGHIJKLMNOPQRSTUVWXYZ234567'
 _b32tab = [bytes([i]) for i in _b32alphabet]
-_b32tab2 = [a + b for a in _b32tab for b in _b32tab]
+_b32tab2 = None
 _b32rev = {v: k for k, v in enumerate(_b32alphabet)}
 
 def b32encode(s):
@@ -155,6 +155,9 @@
         s = s + bytes(5 - leftover)  # Don't use += !
     encoded = bytearray()
     from_bytes = int.from_bytes
+    global _b32tab2
+    if _b32tab2 is None:
+        _b32tab2 = [a + b for a in _b32tab for b in _b32tab]
     b32tab2 = _b32tab2
     for i in range(0, len(s), 5):
         c = from_bytes(s[i: i + 5], 'big')
@@ -284,8 +287,6 @@
         b = b + b'\0' * padding
     words = struct.Struct('!%dI' % (len(b) // 4)).unpack(b)
 
-    a85chars2 = _a85chars2
-    a85chars = _a85chars
     chunks = [b'z' if foldnuls and not word else
               b'y' if foldspaces and word == 0x20202020 else
               (chars2[word // 614125] +
@@ -303,7 +304,7 @@
 _A85START = b"<~"
 _A85END = b"~>"
 _a85chars = [bytes([i]) for i in range(33, 118)]
-_a85chars2 = [(a + b) for a in _a85chars for b in _a85chars]
+_a85chars2 = None
 
 def a85encode(b, *, foldspaces=False, wrapcol=0, pad=False, adobe=False):
     """Encode a byte string using Ascii85.
@@ -324,6 +325,9 @@
     adobe controls whether the encoded byte sequence is framed with <~ and ~>,
     which is used by the Adobe implementation.
     """
+    global _a85chars2
+    if _a85chars2 is None:
+        _a85chars2 = [a + b for a in _a85chars for b in _a85chars]
     result = _85encode(b, _a85chars, _a85chars2, pad, True, foldspaces)
 
     if adobe:
@@ -411,7 +415,7 @@
 _b85chars = b"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ" \
             b"abcdefghijklmnopqrstuvwxyz!#$%&()*+-;<=>?@^_`{|}~"
 _b85chars = [bytes([i]) for i in _b85chars]
-_b85chars2 = [(a + b) for a in _b85chars for b in _b85chars]
+_b85chars2 = None
 _b85dec = None
 
 def b85encode(b, pad=False):
@@ -420,6 +424,9 @@
     If pad is true, the input is padded with "\0" so its length is a multiple of
     4 characters before encoding.
     """
+    global _b85chars2
+    if _b85chars2 is None:
+        _b85chars2 = [a + b for a in _b85chars for b in _b85chars]
     return _85encode(b, _b85chars, _b85chars2, pad)
 
 def b85decode(b):