[koliber]

Implement some none-trivial algorithm and then try to optimize the heck out of it. Focus on the concrete CPU, architecture, cache, and memory in the hardware you have in front of you. Forget portability for a moment.

This comes to mind: https://www.morling.dev/blog/one-billion-row-challenge/

Read how others have done it. Here's an example in Java that goes relatively low-level to squeeze out performance: https://questdb.io/blog/billion-row-challenge-step-by-step/