Map freezezes when loading about (13000) markers

Hi,

We are using leaflet API to populate around 13000 markers.

We found a problem while rendering the markers as it freezes the browser(Chrome) - often requiring us to use task manager and kill process.

We tried a method (In loop):

var marker = new L.Marker(locations, { icon: new markerIcon() });
marker.desc = datum.d;
map.addLayer(marker);

Could you suggest if there is an issue; the way we are using leaflet API? Please advise. 

Thank you,
Rahul