Fusion Tables vs. Postgres with PHP

I'm trying to draw 5 sets ~30k markers to a Google map at a time, which set is drawn depends on user input/selection.

I've noticed very slow load times by the application in rendering the points using the following code.

function set_markers(minyear,maxyear,minprice,maxprice){

  if (window.XMLHttpRequest) {
    xmlhttp = new XMLHttpRequest();
 } else { // code for IE6, IE5
    xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
 }
 // this method is used to capture the response of the http request
 xmlhttp.onreadystatechange = function(){
   if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
     var pinpoints = JSON.parse(xmlhttp.responseText);
     var marker;
     var i=0;
     var lat;
     var lng;
     var price;
     var address;
     var post_latlng;
     var content;
     for (i = 0;i<pinpoints.length;i++){ 
        a=pinpoints[i];
        lat=parseFloat(a["lat"]);
        lng=parseFloat(a["lng"]);
        price=parseFloat(a["price"]);
        address=String(a["address_string"]);
        date=String(a["date_of_sale"]);
        post_latlng = new google.maps.LatLng(lat,lng);
        content ="<b>Address:</b> " + address + "</br>" + "<b>Price:</b>€ " + price + '</br>' + "<b>Date of Sale:</b> " + date;  
        add_marker(address,post_latlng);
        add_InfoWindow(content,marker);
      }
     }
  }
  xmlhttp.open("GET","ajax/pinpoints.php?lat1="+lat1+"&lat2="+lat2+"&lng1="+lng1+"&lng2="+lng2+"&minyear="+minyear+"&maxyear="+maxyear+"&minprice="+minprice+"&maxprice="+maxprice,true);
  xmlhttp.send();
}

function add_marker(add,posit){
  var marker = new google.maps.Marker({  
        map: map, 
        title: add,
        position: posit  
      });
}
function add_InfoWindow(con,mark){
  var infowindow = new google.maps.InfoWindow();
  google.maps.event.addListener(marker,'click', (function(mark,con,infowindow{ 
    return function(){
     infowindow.setContent(con);
     infowindow.open(map,mark);
    };
  })(marker,content,infowindow)); 
 }

I am wondering if using Fusion Tables would speed up this process and still allow me to draw the points as specified in the Javascript code above? If so, how can I call a Fusion Table from my Javascript and store the return in a JSON array so as I can cause minimal disruption to the application when switching from PHP/Postgres to Fusion Tables. I've already created the relevant Fusion Table, I just need to know if and how to connect it?

Suggestions on how to optimise the above code to speed up running time are also welcome.