In addition, every time you hide or unhide a file or folder, that item must be copied and encrypted or decrypted, respectively, which can take time. With small files, the processing time is almost instantaneous, but larger folders (such as a 7GB folder I tested) take significantly longer.
Finally, this processing time wouldn't be as much of an issue if you could preview or edit files while they're in your vault — you wouldn't be swapping your files in and out very often. But you must remove an item from the vault to view or modify it. Similarly, while Hider supports Mavericks' Tags feature, you can't add or modify an item's tags while it's in your vault. (You can, however, create custom groups for your files while they're encrypted.)
Still, despite these nitpicks, Hider works remarkably smoothly. It's a great little tool for anyone looking for a digital hidey-hole, and the encryption is a nice bonus.
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