To be honest, the place I've seen it make a *significant* difference is in the school system in the US - fast processing speed is an advantage in some situations at school. I can't say that I've seen it have any tremendous advantage in the working world I've been a part of (I'm a scientist). So no, I don't think it's a significant difference, just a difference.
polarbear
I agree with polarbear. Processing speed is only really useful in rote memory situations in school and would have little bearing on real world situations. My daughter has a rather slow processing speed and I have a relatively fast processing speed in comparison. However, she is a deep thinker and really delves deeply into what she is working on. She asks and answers the hard questions. Asking the hard questions is what drives discovery and invention! A fast processing speed may help you skip quickly through learning about what others have done, it doesn't help you arrive at original thought.
This is also assuming that someone who can quickly scan through large amounts of material is able to commit any of it to long term memory. I tend to think that processing speed is a very poor measure of intelligence. Can it help you fill in more bubbles on a scantron sheet? Yes...but it doesn't make you better able to understand the material presented.
