I spent weeks optimizing a JavaScript program running on my NVMe SSD with 2.4 billion records, and I finally found out what was slowing it down - me! In a nutshell, I discovered that benchmarking others' code or taking shortcuts can lead to false optimizations. By doing my own benchmarks, controlling the environment (temperature), and prioritizing readability over speed, I achieved significant performance improvements. Don't trust others' claims; do your own benchmarks.