String.charAt.js

var i,n=1000000;
var a="123";
var b=Object(a);

console.time("Primitive.charAt");
i=n;
while(i--)
  a.charAt(0);
console.timeEnd("Primitive.charAt");

console.time("Object.charAt");
i=n;
while(i--)
  b.charAt(0);
console.timeEnd("Object.charAt");

console.time("Primitive.substr");
i=n;
while(i--)
  a.substr(0,1);
console.timeEnd("Primitive.substr");

console.time("Object.substr");
i=n;
while(i--)
  b.substr(0,1);
console.timeEnd("Object.substr");

console.time("Primitive.slice");
i=n;
while(i--)
  a.slice(0,1);
console.timeEnd("Primitive.slice");

console.time("Object.slice");
i=n;
while(i--)
  b.slice(0,1);
console.timeEnd("Object.slice");

console.time("Primitive[]");
i=n;
while(i--)
  a[0];
console.timeEnd("Primitive[]");

console.time("Object[]");
i=n;
while(i--)
  b[0];
console.timeEnd("Object[]");

/*
ff 3.6
Primitive.charAt: 922ms
Object.charAt: 928ms
Primitive.substr: 1067ms
Object.substr: 1088ms
Primitive.slice: 1056ms
Object.slice: 1123ms
Primitive[]: 478ms
Object[]: 538ms

chrome 4
Primitive.charAt: 1070
Object.charAt: 1087
Primitive.substr: 1000
Object.substr: 1122
Primitive.slice: 977
Object.slice: 1112
Primitive[]: 971
Object[]: 955

opera 10.50
Primitive.charAt: 670
Object.charAt: 618
Primitive.substr: 635
Object.substr: 634
Primitive.slice: 644
Object.slice: 633
Primitive[]: 537
Object[]: 503

ie7 n=100000 String[] not supported
Primitive.charAt: 671
Object.charAt: 942
Primitive.substr: 661
Object.substr: 961
Primitive.slice: 651
Object.slice: 952

ie8 n=200000 String[] not supported
Primitive.charAt: 731
Object.charAt: 741
Primitive.substr: 661
Object.substr: 781
Primitive.slice: 661
Object.slice: 832

*/