This is the code that is faster than AJ's code

gistfile1.js

var thingsCount = 0;
var   urls = []
	, deferreds = []
;

var mainDeferred = $.Deferred();
deferreds.push(mainDeferred);

$.get('https://www.lds.org/directory/services/ludrs/unit/current-user-units/',function(r){
    
    JSON.parse(r)[0].wards.forEach(function(ward){
        
        $.get('https://www.lds.org/directory/services/ludrs/mem/wardDirectory/photos/'+ward.wardUnitNo,function(r){
            var hh = JSON.parse(r);
            var wardThings = [];
            //console.log(hh);
            hh.forEach(function(household){
                if(household.photoUrl.length){
                    wardThings.push({
                        ward:ward,
                        household : household
                    });
                }
            });
            var img;
            thingsCount += wardThings.length;
            //console.log()
            wardThings.forEach(function(thing){
				//console.log('hi');
				img = document.createElement('img');
				img.onload = function(){
					var c = document.createElement('canvas');
					var x = c.getContext('2d');
					c.height = this.height,
					c.width = this.width;
					x.drawImage(this, 0,0);
					urls.push({
						name : thing.household.householdName,
						imageData : c.toDataURL('image/jpeg', 0.2)
					});
					if(thingsCount == urls.length){
						mainDeferred.resolve();
					}
				};
				img.src = thing.household.photoUrl;
			});
        });
    });
});

$.when.apply(null, deferreds)
.then(function(){
	$.ajax({
		type:'post',
		processData:false,
		data: JSON.stringify(urls),
		url:'TO BE DETERMINED',
		success: function(r){
			console.log("SERVER SUCCESS RESPONSE:", r);
		},
		error:function(){
			console.log("SERVER ERROR RESPONSE")
		}
	});
});