Step 2 of 6
The CPU and the execution cycle
The processor repeats one loop billions of times a second: fetch the next instruction, decode it, run it. It keeps a few values in super-fast slots called registers. Everything else lives in slower memory.
Why it matters when you build with AI: This is why 'just loop over everything' works fine with 100 rows and falls over with 1 million. The work is real, even if the code looks short.
Quick check
A loop over 1 million rows is slow but the code is only 3 lines. Why?
Code length isn't work. The CPU fetches, decodes and runs each step, a million times.