My brain has been buzzing for he last few days, trying to solve a problem that had me utterly confused. Anyone trying to talk with me during this time may have been greeted with grunts of "leave-me-alone-i'm-thinking"annoyance - sorry about that.

Firefox was sending two identical HTTP requests to the server for every page on a website I was developing. The first response of which was seemingly ignored by Firefox and overwritten with the second. This was effectively doubling the server's load.

After searching for a solution I came across a few sites that had discovered an issue with emtpy "src" attributes in Firefox. My site had no external assets however, so this didn't apply (but a good thing to know for future).