請問有人知道safari webpage preview fetcher 是什麼嗎?

I found this on a board and tried it. Works great with no resulting glitches (so far).

1. Quit Safari 4.0 and right-click on it's icon in the Finder. Select "Show Package Contents".
2. Look inside the Contents folder and right-click on Safari Webpage Preview Fetcher and select Compress "Safari Webpage Preview Fetcher".
3. Put the original Safari Webpage Preview Fetcher in the trash and empty it.
4. Navigate to ~/Library/Caches/com.apple.Safari/Webpage Previews and highlight it. Get Info on it.
5. At the bottom click on the padlock, type in your password and then change the Privilege column for your login name to "Read only" and lock the folder. Close the Get Info window.
6. Launch Safari.