The class was on OS design and others where we would deal with directories on disks you learned that the more files there were the longer it could take for the OS to find and return from the open() api call.

You've shot right past any reasonable number (it was less than 256 files per directory back then) and should be suffering a system slowdown as the OS "works" to find your file.

Even today I keep our file server in under 1K directory entries except where it doesn't matter.

Bob