Just stumbled upon the problem 
Step of 0.1 works fine, step 0.05 diverges and stops on MaxIters, and step 0.025 or less appears to hang Julia, which doesn’t then react to Ctrl-C.
Are there any workarounds known (using some other algorithm instead of NewtonRaphson ??).
Alternative question: If I have a relatively simple 2D stationary diffusion problem, what is currently the way to go?