Tracking slow in FireFox only

[drawlinson]

Hi

Running your demo with the glasses - and the same code locally in testing - I notice that the performance of the tracker is about 3-4 FPS in FireFox on Windows and OSX but easily manages 20+ FPS in FireFox on Linux. Also, the same code executing in Chrome and MS Edge browsers on all operating systems runs at 20+ FPS. I have tested on several machines with Windows 8, 10, and OSX.

There seems to be some fundamental issue with Firefox and the tracker detect() call.

I will dig into it a bit more but it'd be great if you could take a look into it as well. I will update the issue if I find anything and submit a pull request if I can fix it.