diff -r b3f410dbab25 Lib/imaplib.py
--- a/Lib/imaplib.py	Fri May 20 11:49:06 2011 -0500
+++ b/Lib/imaplib.py	Sat May 21 12:06:41 2011 +0200
@@ -22,7 +22,7 @@
 
 __version__ = "2.58"
 
-import binascii, errno, random, re, socket, subprocess, sys, time
+import binascii, errno, cStringIO, random, re, socket, subprocess, sys, time
 
 __all__ = ["IMAP4", "IMAP4_stream", "Internaldate2tuple",
            "Int2AP", "ParseFlags", "Time2Internaldate"]
@@ -1163,23 +1163,22 @@
         def read(self, size):
             """Read 'size' bytes from remote."""
             # sslobj.read() sometimes returns < size bytes
-            chunks = []
+            chunk = cStringIO.StringIO()
             read = 0
             while read < size:
-                data = self.sslobj.read(min(size-read, 16384))
+                data = self.sslobj.read(min(size-read, 4096))
                 read += len(data)
-                chunks.append(data)
-
-            return ''.join(chunks)
+                chunk.write(data)
+            return chunk.getvalue()
 
 
         def readline(self):
             """Read line from remote."""
-            line = []
+            line = cStringIO.StringIO()
             while 1:
                 char = self.sslobj.read(1)
-                line.append(char)
-                if char in ("\n", ""): return ''.join(line)
+                line.write(char)
+                if char in ("\n", ""): return line.getvalue()
 
 
         def send(self, data):