>>195
あははは！お前こそベンチマークとって、自分でたしかめな。

% time ruby -e '1000000.times { [1, 2, 3].sort! { |a, b| a <=> b } }'
ruby -e '1000000.times { [1, 2, 3].sort! { |a, b| a <=> b } }' 11.40s user 0.01s system 99% cpu 11.520 total
% time ruby -e '1000000.times { [1, 2, 3].sort_by { |a| a } }'
ruby -e '1000000.times { [1, 2, 3].sort_by { |a| a } }' 15.58s user 0.00s system 97% cpu 15.922 total