[0] Perl> cmpthese -3,{a=>q[@a = map $_*1, @a],b=>q[map $_*=1, @a],c=>q[$_*=1 for @a] };;
    Rate    a    c    b
a 2.88/s   -- -67% -67%
c 8.64/s 200%   --  -2%
b 8.86/s 208%   3%   --