I was going about making some space on my MacBook's hard drive, when I noticed a massive folder full of images. The folder was 4.5Gb, and was under: /private/var/folders/36/36CUaKVfEna30987Ywkm6k+++TI/-Caches-/com.apple.Safari/Webpage Previews/ As the folder name suggests, this is used for Safari's web preview feature introduced in the Safari 4 Beta. Inside are tens of thousands of images, in JPEG and PNG format (I don't know why both are included). I thought I'd let you all know how much space Safari 4 is eating. I've deleted the folder and am going back to Safari 3!