I wouldn't say the topic is that confusing, there is a lot that could be done on squarespace side, and they should do more as you are paying for SAAS. Its just as a consumer of their product your hands are tied, and your options are accept it or change platform.
For the record our site also loads extremely slowly, into the minutes for pages to render on a slow connection. As mentioned you can reduce image size and quality, but that's about it.