gistfile1.txt

irb(main):036:0> require 'benchmark'
=> true
irb(main):037:0> Benchmark.bmbm do |b|
irb(main):038:1* b.report("+=") do
irb(main):039:2* a = ""
irb(main):040:2> 100_000.times { a += "foo" }
irb(main):041:2> end
irb(main):042:1> b.report("<<") do
irb(main):043:2* a = ""
irb(main):044:2> 100_000.times { a << "foo" }
irb(main):045:2> end
irb(main):046:1> end
Rehearsal --------------------------------------
+=  15.507000   5.413000  20.920000 ( 21.429225)
<<   0.031000   0.000000   0.031000 (  0.040003)
---------------------------- total: 20.951000sec

         user     system      total        real
+=  15.740000   5.273000  21.013000 ( 21.897252)
<<   0.031000   0.000000   0.031000 (  0.036002)
=> [ 15.740000   5.273000  21.013000 ( 21.897252)
,   0.031000   0.000000   0.031000 (  0.036002)
]
irb(main):047:0>