function throttle( fn, time ) {
    var t = 0;
    return function() {
        var args = arguments,
            ctx = this;

            clearTimeout(t);

        t = setTimeout( function() {
            fn.apply( ctx, args );
        }, time );
    };
}

document.addEventListener("DOMSubtreeModified", throttle( function() {
    //code
}, 50 ), false );