I studied Econ in college and been a python guy for last 8 years but have no knowledge of how the machine actually interacts with my code. Is there a formal name for understanding that?
Of course, it can be learned on your own too. But generally this path is harder because it's hard to know what to study. The CS program will expose you to breadth of concepts.
EDIT: Link to course in OpenCourseware if you want to virtually take it: https://ocw.mit.edu/courses/6-004-computation-structures-spr...
To get into the right mindset for SIMD optimization, play Zachtronic games. You have a big pile of odd-shaped tools that take some input and output a result a few cycles later, you have limits on how many instructions can run at once, but maybe you can do something like a load each cycle for free. Run your benchmark, count the cycles, make a small tweak and test again.
It's hard for me to answer, because I was learning everything I could on the internet before undergrad, following each tiny micro-architectural tweak in minute detail. It makes it hard to remember what things college really provided & what was self-taught.
If you’re interested in learning more about microarchitectural optimization I find that getting a basic understanding of how a modern processor has evolved and then reading posts like these (looking things up when necessary) can get you mostly up to speed with the area. Most people don’t use these details in their everyday code so if you’re just looking to make your code fast learning how to measure algorithmic complexity and use a profiler is likely to be much more valuable.