How to compress SumoMe external images

I am using SumoMe share plugin for social promotion in my 2 websites. While loading, it fetches images and JS from sumome domain.

While testing speed of my Site 1, Compress Images section is showing Grade A.
While testing speed of my Site 2, Compress Image section is showing Grade C. When I am checking the things in detail, it is showing 2 sumome image issue [refer Attachment]. I am tried all possible but not getting any possible solution. When I am removing the plugin from the Site 2, Compress Image section is showing A.

I am bit confused, for Site 1 plugin is working well but site 2 it is not working. Please guide, how to debug the issue of sumome or wayout to fix image compression issue related external fetching.[attachment=801]