Obtain better load time!

smaller.js

var tinify = require("tinify");
var walk    = require('walk');
tinify.key = "your key";

var files   = [];

var walker  = walk.walk('./images', { followLinks: false });

walker.on('file', function(root, stat, next) {
    files.push(root + '/' + stat.name);
    next();
});

walker.on('end', function() {
    files.map(function(file){
    	tinify.fromFile(file).toFile(file);
    });
});