Progressive Jpg

How to create Progressive JPG while thumbnail creating?

How to create Progressive JPG while thumbnail creating?

I`m not sure that CS-Cart supports "progressive jpeg" from the box. And I can suggest as the workaround using cron-task with "jpegtran", for example.
Smtng like
find /pathtocscart/public_html/images/thumbnails -name "*.jpg" -type f -exec jpegtran -progressive -copy none -optimize -outfile {} {} \;

Is there a reason you need to run progressive JPG? That is fairly legacy and non-standard for modern website experiences.