I've just checked my website with http://tools.pingdom.com/ and it told me, that my Images are loading too long. I'm using the proxy function in XenForo so that every image can be load over SSH.
My speedresult: http://tools.pingdom.com/fpt/#!/cLV6Qb/https://www.gamerklinik.de/
My webpage: https://www.gamerklinik.de/
Maybe someone can help.