Why WalkingFileTree is faster the second time? <p>I am using the function <code>Files.walkfiletree()</code> from <code>java.NIO</code>, I am looking over a really big tree so when I run the app the first time (with first time I mean each time I turn on my computer) the app takes some time but the second time is really fast. why? is some cache working? Can I use this in some permanent way?</p>