how to fast load a big kml file as billboards

I am beginning developer in the world of Cesium. I have started out with the workshop tutorial and have been modifying it to my needs. I am however experiencing some performance problems regarding the kml loading.

I have a kml file of +-6MB with +-11000 locations in it. I am loading these locations as billboards. There is a considerable waiting time before they appear.

I wonder what the best way is to tackle this problem? The billboards are spread over a great area, so it could be possible to only load the billboards in the currently visible area. I have however no idea how to accomplish this.

Code example:
   var kmlOptions = {
        camera :,
        canvas : viewer.scene.canvas,
        clampToGround : true
     var flyingSitesKML = Cesium.KmlDataSource.load('./Source/SampleData/flyingsites.kml', kmlOptions);

    flyingSitesKML.then(function(dataSource) {
        var flyingSites = dataSource.entities.values;

        for (var i = 0; i < flyingSites.length; i++) {
            var entity = flyingSites[i];
            if (Cesium.defined(entity.billboard)) {
                entity.billboard.verticalOrigin = Cesium.VerticalOrigin.BOTTOM;
                entity.label = undefined;
                entity.billboard.distanceDisplayCondition = new Cesium.DistanceDisplayCondition(10.0, 200000.0);
                var cartographicPosition = Cesium.Cartographic.fromCartesian(entity.position.getValue(;
                var latitude = Cesium.Math.toDegrees(cartographicPosition.latitude);
                var longitude = Cesium.Math.toDegrees(cartographicPosition.longitude);

I am trying to display all the paragliding launch sites in Europe.

**Cesium version**: [1.45]
Brave browser (tried firefox but it is even slower)


This thread contains a thorough explanation of the issue with loading larger data sources into Cesium. You can work with us to get your data converted into 3D Tiles, which will perform much better.



Thanks for the answer.

Maybe I can reduce the load by removing some useless information from the KML.
Does 3D tiles work for billboards? Is there an alternative to billboards I can use that loads faster?



Yes, the current Cesium implementation handles the draft version of Vector Data 3D Tiles, which includes billboards.