Optimize this: make it 10 times faster

Benchmark script::

    import os, sys, time
    null = open(os.devnull, 'wb')
    stdout = sys.stdout
    dt = []
    for loop in range(10):
        sys.stdout = null
        t0 = time.time()
        for subloop in range(100):
            import this
            this=None
            del sys.modules['this']
        dt.append(time.time() - t0)
        sys.stdout = stdout
    print("Best: %.1f ms" % (min(dt)*1000,))

Results:

 * original: 299.8 ms
 * patched: 23.2 ms

diff --git a/Lib/this.py b/Lib/this.py
--- a/Lib/this.py
+++ b/Lib/this.py
@@ -1,4 +1,5 @@
-s = """Gur Mra bs Clguba, ol Gvz Crgref
+#coding:rot13
+cevag("""Gur Mra bs Clguba, ol Gvz Crgref
 
 Ornhgvshy vf orggre guna htyl.
 Rkcyvpvg vf orggre guna vzcyvpvg.
@@ -18,11 +19,4 @@ Abj vf orggre guna arire.
 Nygubhtu arire vf bsgra orggre guna *evtug* abj.
 Vs gur vzcyrzragngvba vf uneq gb rkcynva, vg'f n onq vqrn.
 Vs gur vzcyrzragngvba vf rnfl gb rkcynva, vg znl or n tbbq vqrn.
-Anzrfcnprf ner bar ubaxvat terng vqrn -- yrg'f qb zber bs gubfr!"""
-
-d = {}
-for c in (65, 97):
-    for i in range(26):
-        d[chr(i+c)] = chr((i+13) % 26 + c)
-
-print "".join([d.get(c, c) for c in s])
+Anzrfcnprf ner bar ubaxvat terng vqrn -- yrg'f qb zber bs gubfr!""")