Not working with firefox?

I have recently switched from https to http on my website and it seems to me as if firefox doesn’t load the file from the cache. When looking at the source code in firefox the hypercache tag is missing and the website is pretty slow. When doing this in IE and Chrome the tag is there and the site is 10 times as fast.

What can this be?

https://ww.wp.xz.cn/plugins/hyper-cache/