I ran pybench, even if I know that it's not really revelant: overall 0.3% slowdown. But pybench doesn't look reliable: some tests are faster, which looks like noise in the benchmark.

-------------------------------------------------------------------------------
PYBENCH 2.1
-------------------------------------------------------------------------------
* using CPython 3.5.0a1+ (default:648b35f22b91+, Mar 6 2015, 13:18:57) [GCC 4.9.2 20141101 (Red Hat 4.9.2-1)]
* disabled garbage collection
* system check interval set to maximum: 2147483647
* using timer: time.perf_counter
* timer: resolution=1e-09, implementation=clock_gettime(CLOCK_MONOTONIC)

-------------------------------------------------------------------------------
Benchmark: orig.pybench
-------------------------------------------------------------------------------

    Rounds: 10
    Warp:   10
    Timer:  time.perf_counter

    Machine Details:
       Platform ID:    Linux-3.18.3-201.fc21.x86_64-x86_64-with-fedora-21-Twenty_One
       Processor:      x86_64
    
    Python:
       Implementation: CPython
       Executable:     /home/haypo/prog/python/default/python.orig
       Version:        3.5.0a1+
       Compiler:       GCC 4.9.2 20141101 (Red Hat 4.9.2-1)
       Bits:           64bit
       Build:          Mar  6 2015 13:19:47 (#default:648b35f22b91)
       Unicode:        UCS4


-------------------------------------------------------------------------------
Comparing with: patch.pybench
-------------------------------------------------------------------------------

    Rounds: 10
    Warp:   10
    Timer:  time.perf_counter

    Machine Details:
       Platform ID:    Linux-3.18.3-201.fc21.x86_64-x86_64-with-fedora-21-Twenty_One
       Processor:      x86_64
    
    Python:
       Implementation: CPython
       Executable:     /home/haypo/prog/python/default/python.patched
       Version:        3.5.0a1+
       Compiler:       GCC 4.9.2 20141101 (Red Hat 4.9.2-1)
       Bits:           64bit
       Build:          Mar  6 2015 13:18:57 (#default:648b35f22b91+)
       Unicode:        UCS4


Test                             minimum run-time        average  run-time
                                 this    other   diff    this    other   diff
-------------------------------------------------------------------------------
          BuiltinFunctionCalls:    41ms    41ms   -1.1%    41ms    41ms   -1.5%
           BuiltinMethodLookup:    24ms    24ms   +0.3%    24ms    25ms   -0.8%
                 CompareFloats:    26ms    26ms   +2.2%    27ms    26ms   +1.2%
         CompareFloatsIntegers:    59ms    60ms   -0.9%    60ms    61ms   -2.5%
               CompareIntegers:    38ms    36ms   +4.6%    38ms    37ms   +3.5%
        CompareInternedStrings:    26ms    25ms   +0.6%    26ms    26ms   -0.5%
                  CompareLongs:    22ms    21ms   +1.1%    22ms    22ms   +0.0%
                CompareStrings:    22ms    23ms   -1.3%    23ms    23ms   -1.3%
    ComplexPythonFunctionCalls:    40ms    40ms   -1.5%    40ms    41ms   -2.5%
                 ConcatStrings:    28ms    28ms   -0.3%    28ms    29ms   -1.2%
               CreateInstances:    41ms    42ms   -1.7%    42ms    43ms   -2.6%
            CreateNewInstances:    31ms    32ms   -2.2%    32ms    33ms   -3.2%
       CreateStringsWithConcat:    59ms    56ms   +5.6%    60ms    58ms   +2.7%
                  DictCreation:    43ms    48ms  -10.3%    44ms    50ms  -12.7%
             DictWithFloatKeys:    36ms    37ms   -4.8%    36ms    38ms   -6.0%
           DictWithIntegerKeys:    28ms    29ms   -4.1%    29ms    31ms   -6.4%
            DictWithStringKeys:    24ms    26ms   -8.9%    24ms    27ms  -10.3%
                      ForLoops:    22ms    22ms   -0.9%    22ms    23ms   -2.2%
                    IfThenElse:    31ms    33ms   -5.9%    31ms    34ms   -7.9%
                   ListSlicing:    35ms    35ms   -0.1%    36ms    36ms   -2.0%
                NestedForLoops:    34ms    35ms   -2.3%    34ms    36ms   -4.7%
      NestedListComprehensions:    37ms    37ms   -1.2%    37ms    40ms   -7.6%
          NormalClassAttribute:    77ms    71ms   +8.1%    77ms    74ms   +3.9%
       NormalInstanceAttribute:    37ms    36ms   +2.1%    38ms    38ms   -0.6%
           PythonFunctionCalls:    35ms    34ms   +1.7%    35ms    35ms   -0.5%
             PythonMethodCalls:    45ms    44ms   +3.3%    46ms    45ms   +0.7%
                     Recursion:    60ms    58ms   +3.7%    60ms    59ms   +1.0%
                  SecondImport:    33ms    33ms   -0.0%    33ms    33ms   -1.9%
           SecondPackageImport:    34ms    34ms   +0.1%    34ms    34ms   -2.0%
         SecondSubmoduleImport:    83ms    86ms   -3.5%    85ms    87ms   -2.4%
       SimpleComplexArithmetic:    23ms    23ms   +0.7%    23ms    24ms   -2.2%
        SimpleDictManipulation:    51ms    53ms   -3.8%    52ms    55ms   -5.7%
         SimpleFloatArithmetic:    24ms    24ms   +0.3%    24ms    25ms   -2.0%
      SimpleIntFloatArithmetic:    31ms    30ms   +1.1%    31ms    31ms   -0.1%
       SimpleIntegerArithmetic:    30ms    30ms   +0.0%    30ms    31ms   -2.0%
      SimpleListComprehensions:    30ms    32ms   -4.6%    31ms    33ms   -5.7%
        SimpleListManipulation:    27ms    26ms   +2.4%    27ms    27ms   +0.4%
          SimpleLongArithmetic:    21ms    21ms   +2.1%    22ms    22ms   +0.2%
                    SmallLists:    36ms    36ms   -1.3%    36ms    37ms   -3.0%
                   SmallTuples:    43ms    43ms   -0.5%    44ms    45ms   -2.5%
         SpecialClassAttribute:    75ms    72ms   +4.3%    75ms    73ms   +2.5%
      SpecialInstanceAttribute:    38ms    41ms   -7.7%    38ms    42ms   -9.0%
                StringMappings:    77ms    76ms   +1.4%    77ms    78ms   -0.3%
              StringPredicates:    43ms    44ms   -2.6%    44ms    45ms   -3.9%
                 StringSlicing:    39ms    38ms   +3.2%    39ms    39ms   +1.0%
                     TryExcept:    21ms    21ms   -2.8%    21ms    22ms   -4.8%
                    TryFinally:    29ms    29ms   +0.2%    29ms    29ms   -1.2%
                TryRaiseExcept:    11ms    11ms   -0.2%    11ms    11ms   -1.1%
                  TupleSlicing:    42ms    43ms   -0.8%    45ms    45ms   +0.5%
                   WithFinally:    45ms    45ms   -0.8%    45ms    45ms   -1.2%
               WithRaiseExcept:    36ms    36ms   -0.9%    36ms    36ms   -1.5%
-------------------------------------------------------------------------------
Totals:                          1920ms  1927ms   -0.3%  1941ms  1980ms   -2.0%

(this=orig.pybench, other=patch.pybench)