[nOobCrafter]

... извиняюсь, ерунду написал, метод с масисвов более быстр:

function sliceStr(str:String):Void
{
	var strLength:Number = str.length;
	for (var i:Number = 0; i < strLength; i++)
	{
		var curLetter:String = str.slice(i, (i + 1));
	}
}
function subStr(str:String):Void
{
	var strLength:Number = str.length;
	for (var i:Number = 0; i < strLength; i++)
	{
		var curLetter:String = str.substring(i, (i + 1));
	}
}
function splitStr(str:String):Void
{
	var strArr:Array = str.split('');
	var strLength:Number = strArr.length;
	for (var i:Number = 0; i < strLength; i++)
	{
		var curLetter:String = strArr[i];
	}
}
 
var count:Number = 1000;
t = getTimer();
for(var i:Number = 0; i < count; i++)
{
	sliceStr('I know, what you were doing last summer...');
}
trace(getTimer() - t);
t = getTimer();  // 185
for(var i:Number = 0; i < count; i++)
{
	subStr('I know, what you were doing last summer...');
}
trace(getTimer() - t);  // 189
t = getTimer();
for(var i:Number = 0; i < count; i++)
{
	splitStr('I know, what you were doing last summer...');
}
trace(getTimer() - t);  // 76