While this is arguably true for software that directly faces a human being, embedded/specialist applications are getting faster and more powerful. I work on a massively parallel ASIC and it benefits from every iteration of die shrink with clock speed.
If there is a machine intelligence it won't be written in Mono or Python on a standard PC - it will be a specially crafted piece of silicon with very well optimised process code.
I do believe we will reach a singularity where us squishy meatbags make ourselves redundant, but I don't fear it. If the culmination of mankind produces an intelligence that surpasses our own, that's a great end-goal. It/they will certainly be better physically equipped to explore the stars, perhaps carrying a memory of the seeds of their creation with them.
What is curious is why we haven't yet encountered such machines. I guess as a planet we've not been pumping out giveaway radio waves for long enough?