In my own experience, using cuda when you have access to an NVIDIA card increases the speed even more so. Perhaps you might want to add a comparison to that too. I used to make fractals too and went through the same steps :D
So, I've got to admit, I don't really Java. But I'm really curious what's going on in that first question. The blog post says "T is replaced with Exception"... but the type parameter that was given was "RuntimeException." Does the compiler just ignore that type parameter and work within the context of that function?