There are quite some complaints and solutions about Firefox displaying annoying "unresponsive JavaScript detected, continue?" messages.

If you have scripts that simply sometimes take longer to do their stuff, you shouldn't however force your visitors to change the default JavaScript "timeout" value as proposed by the tips linked above. You should consider doing parts of your calculations asynchronously and give free the one and only JavaScript execution thread for some milliseconds. Firefox will be happy in this case and won't display the annoying message anymore, even when configured with its default settings.

I did that with the latest version 0.12 of RUZEE.Borders. Let's have a look at the main rendering loop: