I have a problem using the markers.

create a container with just points and try implementing the following as an eventobserver function that load once panning or zooming is finished...

so when the data comes in...load them into an array
==================
for (var r in res) {

var lat:Number = res[r].Latitude[0];
var lon:Number = res[r].Longitude[0];

var loc = new Location( lat, lon );

var tit:String = res[r].Title ? ' ' + res[r].Title[0] + '

': _mapPointHeader ? _mapPointHeader : '';
var desc:String = res[r].Description ? ' ' + res[r].Description[0] + '

': _mapPointBody ? _mapPointBody : '';
_mapPoints.push({id:points, tit:tit, desc:desc, loc:loc});

_extent.push(loc);

//_map.putMarker(points, loc);

points++;

}

these are the observers that fire ( check out casa )

_map.addEventObserver(this, Map.EVENT_START_PANNING, 'removePoints');
_map.addEventObserver(this, Map.EVENT_STOP_PANNING, 'adjustPoints');

_map.addEventObserver(this, Map.EVENT_START_ZOOMING, 'removePoints');
_map.addEventObserver(this, Map.EVENT_STOP_ZOOMING, 'adjustPoints');

and then have this function fire after every event to the map ( panning zooming ) is finished...
===================
private function adjustPoints() {
for ( var p in _mapPoints ) {

// var pnt = _map.mapPointToPoint( _mapPoints[p].id, _pointsContainer );
// trace('pnt: ' + pnt);

var pointXY:Object = _map.locationPoint( _mapPoints[p].loc, _pointsContainer );

// make sure it's in the bounds of the points container
if (pointXY.x > 0 && pointXY.x <= (_pointsBoundsW - 20) && pointXY.y > 20 && pointXY.y <= _pointsBoundsH) {
var point = _pointsContainer.attachMovie('map_point', 'map_point' + _pointsContainer.getNextHighestDepth(), _pointsContainer.getNextHighestDepth(), {_x:pointXY.x, _y:pointXY.y, id:p});
if (_mapPoints[p].tit.length > 0) {
point.addEventObserver(this, EventMovieClip.EVENT_ROLL_OVER, 'popUpOn');
point.addEventObserver(this, EventMovieClip.EVENT_ROLL_OUT, 'popUpOff');
point.addEventObserver(this, EventMovieClip.EVENT_RELEASE_OUTSIDE, 'popUpOff');
}

}
}
}

removing the points
=========================
private function removePoints() {

for ( var p in _pointsContainer ) {

_pointsContainer[p].removeEventObserversForScope(this);
removeMovieClip(_pointsContainer[p]);

}
}