Resize images to a smaller size in responsive mode on mobile devidces

Hi,

I have uploaded all product images at 403px x 403px.

And set the woocommerce images like this: https://tinypic.com/view.php?pic=15zmtlt&s=8#.VAcBTPldV2A

So when the website is in responsive mode. it displays catalog images fine: https://tinypic.com/view.php?pic=5oecjp&s=8#.VAcBmPldV2A

But ive noticed since doing this, the pages take longer to load? as i think they are calling up 403 x 403 instead of a smaller one: https://i60.tinypic.com/2h4cd95.jpg

Is there any way for wordpress/woocommerce to call on the image size that is right for the responsive mode that is being viewed. So the website is as fast as possible?