Multiple occurances during a trace() output request along with suggested fix

This is what you'd expect, and what I see too. The slow trace speed is because trace is a debug tool, and at each step Espruino is searching through all variables to see if it can figure out if any of them have a 'global' name. Normally it's pretty quick but the Wifi code is complex enough that it takes a while to scan through everything.

Let's look at trace2.swf - it seems the video wasn't left running long enough to show any of the repetition, but...

You can see what I think is the mqtt.connect function being dumped, with its scope as "\xFFsco" (mentioned above) which is the big area you're seeing repeated.

You can then see subscribe which is another mqtt function. The video stopped here, but since it's a function declared in the same scope you'd see another identical "\xFFsco"

But it's pretty obvious it's not getting in an endless loop, because each time the function name being printed is different each time.