The one feature I always find myself looking for is the ability to see what a websocket request is sending or receiving. Right now the response tab just says “No response data available for this request”.
Thank you @agronick, this has come up a lot over the years and even more recently. The feature is being worked on and tracked in https://bugzilla.mozilla.org/show_bug.cgi?id=885508 . We expect to have something ready by Firefox 70.