JavaScript performance crap

performance.md

var a = "bla";
for (var i = 0; i < 500000; i++) {
  a += "bla";
}

Is a little faster than

var a = "bla";
for (var i = 0; i < 500000; i++) {
  a = a +" bla";
}

http://jsperf.com/plusequals-vs-var-equals-var-plus-bla