In help from a web designer on a scaling problem

I’m using a theme call TrueMag from themeforest http://themeforest.net/item/true-mag-wordpress-theme-for-video-and-magazine/6755267

I did a http://gtmetrix.com test on my website http://www.militarysurprise.com/ and it said

The following images are resized in HTML or CSS. Serving scaled images could save 872.6KiB (62% reduction).

This thing gave it an F and reduced the grade.

I did a search on the authors comments and they know about the problem this is what they said about it.

You got a F due to scaled images, which is a critical point in a responsive theme. Images are often larger than needed, so they are considered “not optimized”. That cannot be solved. You can, however, prepare proper image size and compress images before uploading so it reduces loading time.

You can increase the loading speed of images by using CDN feature in your cache plugin.

Best regards,

CactusThemes

The question has come up on their comments section many times and they give the same answer in different wording.

WordPress gives three sizes to scale images why wouldn’t the theme use them and still be (responsive) mobile friendly.

Can a theme designer please confirm what they are saying that there is nothing that can be done with it. and if there is please tell me what I can say to them to fix this.

thanks

Mitch