for (var i = 0; i < 20000; i++) {
	trace(i);
}

for (var i = 0; i<20; i++) {
	for (var j = 0; j<1000; j++) {
		trace(1000*i + j);
	}
}

function bigLoop(func, iMin, iMax, jMin, jMax) {
	this.i = iMin;
	for (var j = jMin; j<=jMax; j++) {
		func(this.i, j);
	}
	if (this.i<iMax) {
		this.i++;
		this.onEnterFrame = function() {
			bigLoop(func, this.i, iMax, jMin, jMax);
		};
	} else {
		delete this.onEnterFrame;
		delete this.i;
	}
}

bigLoop( function (i, j) {trace(1000*i + j);}, 
			 0, 19, 0, 999 );