Oh that sucks. If you don't mind helping me troubleshoot the issue: Does this also happen with a Chromium based browser? Any chance you could profile using Firefox's web tools and send it to me (Find my details on twitter.com/cpojer or on the bottom of cpojer.net).

Firefox has not been a focus for the game as it mostly ships on Chromium/WebKit based browsers/app wrappers, but the landing page should still work great.