dimus dimus - 4 months ago 8
Ruby Question

Is there a performance gain in using single quotes vs double quotes in ruby?

Do you know if using double quotes instead of single quotes in ruby decreases performance in any meaningful way in ruby 1.8 and 1.9.

so if I type

question = 'my question'


is it faster than

question = "my question"


I imagine that ruby tries to figure out if something needs to be evaluated when it encounters double quotes and probably spends some cycles doing just that.

Answer
$ ruby -v
ruby 1.9.3p0 (2011-10-30 revision 33570) [x86_64-darwin11.0.0]

$ cat benchmark_quotes.rb
# As of Ruby 1.9 Benchmark must be required
require 'benchmark'

n = 1000000
Benchmark.bm(15) do |x|
  x.report("assign single") { n.times do; c = 'a string'; end}
  x.report("assign double") { n.times do; c = "a string"; end}
  x.report("concat single") { n.times do; 'a string ' + 'b string'; end}
  x.report("concat double") { n.times do; "a string " + "b string"; end}
end

$ ruby benchmark_quotes.rb 

                      user     system      total        real
assign single     0.110000   0.000000   0.110000 (  0.116867)
assign double     0.120000   0.000000   0.120000 (  0.116761)
concat single     0.280000   0.000000   0.280000 (  0.276964)
concat double     0.270000   0.000000   0.270000 (  0.278146)

Note: I've updated this to make it work with newer Ruby versions, and cleaned up the header, and run the benchmark on a faster system.

This answer omits some key points. See especially these other answers concerning interpolation and the reason there is no significant difference in performance when using single vs. double quotes.