I built an ARM64 assembly lexer (well, I generated one from my own parser generator, but this post is not about that) that processes Dart code 2x faster than the official scanner, a result I achieved using statistical methods to reliably measure small performance differences. Then I benchmarked it on 104,000 files and discovered my lexer was not the bottleneck. I/O was. This is the story of how I accidentally learned why pub.dev stores packages as tar.gz files. The setup I wanted to benchmark my...