The optimal code depends of each micro-architecture, and there are plenty of different x86 ones deployed everywhere, so you need to know a little bit of each.
Transferring that expertise to ARM or POWER isn't that difficult either. They're more different, but the same principles still apply.

Most of the time though, optimizations are entirely portable. Using the cache well for example, can be done in a way that is independent on the cache and cache line size in certain scenarios, and in others you can use a portable function to fetch the size.

Actually, people who have high levels of knowledge usually expect anyone working in science to know a lot as well, as they're aware of the vast diversity of things and their own lack of knowledge in many areas.
People who think they know more than others usually only have a superficial understanding of things.

My job is to optimize some other people's code.
You'd be impressed how many people have no idea how to program to use caches effectively.
People than know pipelines how to make the most of the pipeline are even rarer.

words not worlds, sorry.

I'll never understand the people that confuse "premier" and "premiere", they are completely different worlds and aren't even pronounced the same. I've seen it in a slashdot summary a couple of days back too, that's pretty horrible.

I'm sorry if you felt hurt by my comment, it wasn't my attention. I never said that I detest anyone.
I am a software engineer in a specific field, and I have specific needs, different than yours.

Like I said, I don't expect people working in different fields to understand, because they don't really know what I need to do, just like I don't really know what they need to do.

My point was that for a segment of the population, Linux is already the best desktop and workstation operating system.

This is both stupid and cool.

Just put them in the cloud and let another company take care of it.

Aren't the nanoscale structures of carbon more interesting?
Carbon seems to be stronger and lighter than iron. Why do we even mix the two together?

What really is the difference?
If you want your slaves/servants/employees to generate value for you continuously, you have to give them the illusion of giving selflessly.

Different demographics use different things.
I'm a software engineer, with a focus on low-level programming and performance, and as far as I'm concerned, all competent people in my field use Linux daily, be it for work or leisure.

I've tried using Windows or Mac OS X, and even with the various extras you need to install to make those on par, they are still light years behind in terms of usability and productivity.
I don't expect Windows or Mac OS X users to understand. From my experience, when I'm forced to use OS X for example and that I ask an OS X user how to do any simple basic thing, he just answers "I don't know. I just don't do that. Maybe you can purchase a third-party app for it.". People that are satisfied with those operating systems are people with simple needs that follow standard one-size-fits-all workflows, they don't even realize you can do so much more with a real operating system you're in control of, where huge capabilities are just at the touch of your fingertips.

My bad, I wasn't explicit enough.
Civil war is still a thing, what has become obsolete is war between nation-states.

It means you don't know that in French, nouns in the plural form usually take an 's' at the end, same as in English?

War has been obsolete for half a century already.
It seems the only ones that didn't get the memo are the US, who still went to war with Iraq, ruining their economy and political standing.

From your comment, I expected the link to point to something related to Space Battleship Yamato.
Good to know old 'Murrica is making japanese sci-fi real.