bench.js

var s = "translate(-320px, 0)";
var iter = 1000000;

var substr = function() {
  for(var i = 0; i < iter; i++) {
    parseInt(s.substring(s.indexOf('(')+1, s.indexOf(",")-2))
  }
}

var substr_const = function() {
  for(var i = 0; i < iter; i++) {
    parseInt(s.substring(10, 14))
  }
}

var regexp = function() {
  var r = /[\d-]+/
  for(var i = 0; i < iter; i++) {
    parseInt(s.match(r)[0])
  }
}

var regexp_thrash = function() {
  for(var i = 0; i < iter; i++) {
    parseInt(s.match(/[\d-]+/)[0])
  }
}

var regexp_split = function() {
  var r = /[\d-]+/
  for(var i = 0; i < iter; i++) {
    parseInt(s.substr(10).match(r)[0])
  }
}

var regexp_g = function() {
  var r = /[\d-]+/g
  for(var i = 0; i < iter; i++) {
    parseInt(s.match(r)[0])
  }
}

var split = function() {
  var r = /[(),]/
  for(var i = 0; i < iter; i++) {
    parseInt(s.split(r)[1])
  }
}

var bench = function(f, n) {
  var start = (new Date()).getTime()
  f();
  var delta = (new Date()).getTime() - start;
  console.log( n, delta, delta / iter )
}

bench(substr, "substring")
bench(substr, "substr_const")
bench(regexp, "regexp")
bench(regexp_thrash, "regexp_thrash")
bench(regexp_g, "regexp_g")
bench(regexp_split, "regexp_split")
bench(split,  "split")

results.txt

substring 1038 0.001038
substr_const 1030 0.00103
regexp 662 0.000662
regexp_thrash 675 0.000675
regexp_g 912 0.000912
regexp_split 685 0.000685
split 829 0.000829