Tips for rendering Overlays on Google map

If there are more than thousands of Overlays (Markers, Polylines and Polygons) to be displayed on a Google map it starts to get slow due to browser javascript performance and network throughput limits. To maintain high performance, you can use the following techniques

• Only the overlays that are to be shown in the current map are sent to the browser from backend
• If the map is panned or zoomed, only the differences to the visible set are sent
• Polylines and Polygons are clipped to the visible rectangle so that only the visible parts of the lines are sent
• At lower zoom levels

Cluster markers are used in place of actual markers
Polylines and Polygons are simplified to reduce the number of points

• At even lower zoom levels, 256 x 256 tile images are generated with the marker images, polyline sand polygons drawn on them.
• These tiles are cached on disk once generated.