Hello Dejan,
I will let the people know that you suspect my environment.
I marked this as a five-star review but it should have been considerably lower. I am still cleaning up after this plugin.
Now I remembered that I feedled with Minify CSS yesterday. Unchecked CSS in minify and pictures are back.
This means that my CSS is not optimized at all but speed is still a lot better than uncached.
I have temporarily disabled the related posts in Papercuts and running Jetpack related posts, as a temporary solution.