I have worked on a filesystem with 225 million files in a single directory, hosted on ZFS. Operations like `ls` took a minute or so to execute, but creating or

I have worked on a filesystem with 225 million files in a single directory, hosted on ZFS. Operations like `ls` took a minute or so to execute, but creating or accessing a file in this directory was almost the same speed as in an empty directory. I later replaced this filesystem with an sqlite database, which provided a pretty great speedup in table-scan type operations.