It's not straightforward because the file system itself is going to cache some of the info needed to find the files. In other words, when you search the first time, nothing is cached in the file system. So the second time you search, even if you don't change anything, it should be faster. The file system will still have fast access to some of the intermediate structures is used to get the files and possibly some of the files themselves. Basically at every step you need to run the search several times to take the file system caching into account.