In the Chrome developer tools, under the network tab, I'm curious to know what is happening during the gaps. If you look at my image below, I have highlighted in orange the areas where these gaps exist. Where I'm able to load a lot of my page from cache it's a shame these large gaps occur as they make up most of my page load time. What exactly is happening in this time?

EDIT

Okay I found this answer which essentially sums up my question, so a different question: does anyone know a good method to reduce the length of these gaps? Presumably (albeit rather extreme) if I loaded all my CSS on the page there wouldn't be a delay after loading the CSS file before the images were loaded.