// http://jquery.com/
document.querySelector("input").type = "radio";
var tests = [":radio", "input:radio", "[type='radio']", "input[type='radio']", ".page :radio", ".page input:radio", ".page [type='radio']", ".page input[type='radio']"], test;
for (var q=0; q<tests.length; ++q) {
  test = tests[q];
  console.time(test);
  for (var w=0; w<65536; ++w) {
    $(test);
  }
  console.timeEnd(test);
}

ЯБ
:radio: 19756.383ms
input:radio: 6137.169ms
[type='radio']: 1417.999ms
input[type='radio']: 1089.966ms
.page :radio: 20760.277ms
.page input:radio: 7463.510ms
.page [type='radio']: 1366.917ms
.page input[type='radio']: 1110.233ms

FF
:radio: timer started
:radio: 16997.41ms
input:radio: timer started
input:radio: 2165.49ms
[type='radio']: timer started
[type='radio']: 1587.23ms
input[type='radio']: timer started
input[type='radio']: 1382.26ms
.page :radio: timer started
.page :radio: 17737.79ms
.page input:radio: timer started
.page input:radio: 3099.62ms
.page [type='radio']: timer started
.page [type='radio']: 1611.6ms
.page input[type='radio']: timer started
.page input[type='radio']: 1397.61ms

IE11:
:radio: 36 693.039ms
input:radio: 4 326.591ms
[type='radio']: 7 401.012ms
input[type='radio']: 2 546.947ms
.page :radio: 38 798.737ms
.page input:radio: 6 633.429ms
.page [type='radio']: 7 801.181ms
.page input[type='radio']: 2 727.563ms