Image quality problem

Hello.

I use Skitter Slideshow for a long time in the front page of both of my websites (https://www.gamefm.com.br and https://www.tecnoetc.com.br) without any kind of problem.

But, out of nowhere, the image quality of the slideshow of both sites is really bad. I guess that has something with the 3.5/3.5.1 update in WordPress. The slideshow has a custom size of 900X350, and all the featured images has the exact same size. The slideshow image quality used to be superb.

Is this happening to anyone else? Does anyone know what might be happening?

Thank you and sorry my bad english. ??

https://www.ads-software.com/extend/plugins/wp-skitter-slideshow/