MarkerManager v3 | written on:  2013-02-24 12:39:08  
How it Works: The MarkerManager places its markers onto a grid, similar to the map tiles. When the user moves the viewport, it computes which grid cells have entered or left the viewport, and shows or hides all the markers in those cells. (If the users scrolls the viewport beyond the markers that are loaded, no markers will be visible until the EVENT_moveend triggers an update.) In practical consequences, this allows 10,000 markers to be distributed over a large area, and as long as only 100-200 are visible in any given viewport, the user will see good performance corresponding to the 100 visible markers, rather than poor performance corresponding to the total 10,000 markers. Note that some code is optimized for speed over space, with the goal of accommodating thousands of markers. For a description and examples of how to use this library, check out the how-to.