I want to troubleshoot errors that google gives me with the question of the burden of the site, you could help with the issue of the cache of your template, just write the points below
This is all want you can do, you can reduce more images but only with loss of its quality. News Pro GK4 have option to change quality of thumbnails, try to reduce a little bit more.
p.s. The HTTP server response time is the most relevant metric from the users’ point of view. However, the HTTP request response time depends on network traffic, server load and document size.