I have been using Octoprint (1.3.9 running on A Pri3 & OctoPi 0.15.0PE) for some weeks with little issue and connect to us using Firefox under Win7 and Safari on an iPad.
But suddenly I have found that on my PC (Firefox) as soon as I hit the "Control" section, the browsers tab hangs. Generally I see the "Webcam Stream Loading" message, but occasionally a still frame appears.. But after this the browser is totally unresponsive and has to be restarted..
Looking at the task manager, Firefox's starts to consume a huge amount of memory... When I launch Octoprint Firefox is using around 300MB.. But as soon as I hit the 'control' button, it immediatly ramps up for over 2.5GB at which point I have to either close the tab, or even kill the Firefox process.
I tried with Chrome and IE (Although IE does not open the Webcam) thats perfect.
I have also found that Safari on my iPad works fine, so this just appears to be a Firefox issue.. As a final test I tried with my works laptop and I get the same behavour (i.e Chrome is fine, but Firefox not).
So this seems to be a general firefox issue.. I hope there is a solution to this as I am a Firefox user and Octoprint is totally unusable for me right now..