One of the problems with a Google map and really with any other online mapping system is how to handle large amount of locations or markers (pins) on the map.
Some users require to display large number of pins on their maps, so plotting thousands of map points on a map can quickly lead to a degraded user experience.
When you have too many pins of the map this can cause visually overcrowded map and a slow loading time and sluggish interaction with the map.
In order to overcome this poor performance we have added the marker clusters functionality.
This marker's management technique will group nearby pins that will restrict the amount of markers rendered on the map.
Markers clusters is turned Off by default, but you can turn it On if you want to.
We recommend to turn clusters On if you have a large amount of pins on your map.