sounds impossible to even index and classify files so fast. What hardware?

Let's say 100k files is 300k syscalls, at ~1-2us per syscall. That's 300ms of syscalls. Then assume 10kb per file, that's 1GB of file, easily done in a fraction of a second when the cache is warm (it'll be from scanning the dir). That's like 600ms used up and plenty left to just parse and analyze 100k things in 2s.

I’m assuming they meant 100kloc rather than 100,000 files of arbitrary size (how could we even tell how impressive that is without knowing how big the files are?)