[Inevitable off-topic discussion ensues]

With a large amount of files (and with hundreds of directories, we can assume there are a large amount of files. Either that or someone has designed a very bad filesystem layout), using -exec with find can be substantially slower than using xargs. The reason being that -exec forks once for every file, whereas xargs will pack as many arguments on a single command line as possible. This is not only conceptually cleaner (imho), but like I said, with lots of files it's noticeably faster.

Update: Just to test my assertions, I ran a test to see what the difference was. As you can see, the directory I'm running this in has 29,388 files. Granted this benchmark might not be representative of the actual post, but the difference is quite dramatic. Maybe I've done something wrong:

$ time find ./ -type f | wc -l
29388
 
real    0m0.244s
user    0m0.034s
sys     0m0.181s

$ time find ./ -type f -print0 | xargs -0 ls | wc -l
29388
 
real    0m1.049s
user    0m0.420s
sys     0m0.588s

$ time find ./ -type f -exec ls '{}' \; | wc -l
29388
 
real    0m46.239s
user    0m16.509s
sys     0m25.974s
[download]

I ran each test multiple times, and posted the lowest time for each.