Running the tests like `-type l` or `-perm` or whatnot surely can be slow, but that is not in play in the article's use case. In my experience, fast vs. slow "

Running the tests like `-type l` or `-perm` or whatnot surely can be slow, but that is not in play in the article's use case. In my experience, fast vs. slow "reputations" are sadly very unreliable. Here is some system call color. $ find | wc -l 79348 $ strace -c find >/dev/null % time seconds usecs/call calls errors syscall ------ ----------- ----------- --------- --------- ---------------- 29.57 0.039172 1 24453 fcntl 24.51 0.032477 1 19615 close 19.87 0.026329 1 14724 newfstatat 16.78 0.022229 2 9786 getdents64 7.48 0.009909 2 4948 6 openat 0.86 0.001137 1 755 write ... ------ ----------- ----------- --------- --------- ---------------- 100.00 0.132487 1 74336 9 total $ dents find|wc -l 79348 $ strace -c dents f >/dev/null % time seconds usecs/call calls errors syscall ------ ----------- ----------- --------- --------- ---------------- 42.43 0.018491 3 5084 getdents64 28.69 0.012503 2 4896 openat 25.40 0.011071 2 4896 close 3.47 0.001514 2 755 write ... ------ ----------- ----------- --------- --------- ---------------- 100.00 0.043579 2 15697 2 total So, you know, almost 5x the system call count. (EDIT: and yes, yes, not all syscalls are created equally. In this hot cache case there are so many that syscall overhead alone could be a large fraction of costs, though.) But you don't need to trust me. It's probably about 50 lines of C to code up a file tree walk recursion and test it yourself.