I don't think it's a bandwidth problem. Here's a profile I captured in Firefox:

https://i.imgur.com/RJkD3YC.png

All of those image thumbnails were waiting on a single server response that took 9 seconds. This is repeatable: on each load, one or two requests take 10x longer than the rest. They're not large files, in fact most of them are already in the browser cache, and aren't resent (HTTP 304).

(Not an expert).