As a general practice, use http://www.webpagetest.org, or similar tools to regularly measure your page load performance during the entire scope of your project. If you are using http://www.webpagetest.org, you should target a maximum speed index metric of 3000, ideally striving for a value of less than 2000.

You should also consider using the Chrome Developer Tools timeline to review how different elements in your pages load under different circumstances.