Moving the image upload folder to subdomain- Good or Bad

I’ve come across several articles that encourage moving the image upload folder to a sub-domain in order to speed up page loads. Before taking the plunge, I just wanted to know if this good practice or something WordPress developers would encourage?

What makes this even more appealing is that by default WordPress uploads images into so many folders making it hard to track them down. And WP 3.8 doesn’t give the option of defining an image upload path.