Why Google Map loading slowly in FireFox?

Why Google Map loading slowly in FireFox?

I am developing a web application project. In that I am using Google maps
API V3.
function initialize() {
var address = null;
var city = document.getElementById("city").value;
address= city;
var geocoder = new google.maps.Geocoder();
geocoder.geocode({ 'address': address }, function (results, status) {
if (status == google.maps.GeocoderStatus.OK) {
latitude = results[0].geometry.location.lat();
longitude = results[0].geometry.location.lng();
var latlng = new google.maps.LatLng(latitude, longitude);
var settings = {
zoom: 12,
center: latlng,
mapTypeControl: true,
mapTypeControlOptions: {style:
google.maps.MapTypeControlStyle.DROPDOWN_MENU},
navigationControl: true,
navigationControlOptions: {style: google.maps.NavigationControlStyle.SMALL},
mapTypeId: google.maps.MapTypeId.ROADMAP};
var map = new google.maps.Map(document.getElementById("map_canvas"),
settings);
var companyImage = new google.maps.MarkerImage('img/marker.png',
new google.maps.Size(40,40),
new google.maps.Point(0,0)
new google.maps.Point(10,35)
);
var companyShadow = new google.maps.MarkerImage('',
new google.maps.Size(40,40),
new google.maps.Point(0,0
new google.maps.Point(35, 30));
var companyPos = new google.maps.LatLng(latitude, longitude);
var companyMarker = new google.maps.Marker({
position: companyPos,
map: map,
icon: companyImage,
shadow: companyShadow,
title:address,
zIndex: 3});
}
});
}
Marker Image loaded fastly in Internet Explorer and Google Chrome. But in
Mozilla firefox marker image takes some more time to load. After first
loading of marking image, second time image loaded faster.How to clear
issue in Firefox also in safari browser?
http://maps.googleapis.com/maps/api/js?sensor=false