benchmark

Your version
ruby benchmarks/encoding.rb
Rehearsal ---------------------------------------------------------
positive encode:        2.730000   0.010000   2.740000 (  2.725146)
positive can_encode?:   2.470000   0.000000   2.470000 (  2.472397)
negative encode:        3.440000   0.000000   3.440000 (  3.446421)
negative can_encode?:   2.580000   0.000000   2.580000 (  2.578184)
common encode:          1.730000   0.000000   1.730000 (  1.732213)
common can_encode?:     0.540000   0.000000   0.540000 (  0.544492)
----------------------------------------------- total: 13.500000sec

                            user     system      total        real
positive encode:        2.740000   0.000000   2.740000 (  2.742134)
positive can_encode?:   2.450000   0.000000   2.450000 (  2.450048)
negative encode:        3.440000   0.000000   3.440000 (  3.441110)
negative can_encode?:   2.550000   0.000000   2.550000 (  2.557917)
common encode:          1.740000   0.010000   1.750000 (  1.739130)
common can_encode?:     0.550000   0.000000   0.550000 (  0.542363)

Current git version:
ruby benchmarks/encoding.rb
Rehearsal ---------------------------------------------------------
positive encode:        0.960000   0.000000   0.960000 (  0.956984)
positive can_encode?:   0.010000   0.000000   0.010000 (  0.014623)
negative encode:        1.540000   0.000000   1.540000 (  1.532644)
negative can_encode?:   0.010000   0.000000   0.010000 (  0.018297)
common encode:          0.360000   0.000000   0.360000 (  0.358792)
common can_encode?:     0.010000   0.000000   0.010000 (  0.010486)
------------------------------------------------ total: 2.890000sec

                            user     system      total        real
positive encode:        0.950000   0.000000   0.950000 (  0.947739)
positive can_encode?:   0.020000   0.000000   0.020000 (  0.014418)
negative encode:        1.530000   0.000000   1.530000 (  1.535480)
negative can_encode?:   0.020000   0.000000   0.020000 (  0.018089)
common encode:          0.360000   0.000000   0.360000 (  0.360162)
common can_encode?:     0.010000   0.000000   0.010000 (  0.009587)

ruby -v
ruby 2.0.0p247 (2013-06-27 revision 41674) [x86_64-darwin12.4.0]