"Commonly, developers further decrease the size of these objects using base64 encoding, which can reduce images more than 30 percent."
No, not as such. Base64 encoding allows the inclusion of binary data using ASCII, by representing each three bytes of the original binary in _four_ bytes of ASCII. So, rather than reducing the size of an image by 30% (which is unlikely without lossy compression), it guarantees to _increase_ it by at least 33%.
Base64 is the *exact opposite* of compression.
Additionally, the comments about having to update whole pages when included data are changed are misleading. Typically, the data are inserted using server-side includes (see http://httpd.apache.org/docs/1.3/howto/ssi.html), so the underlying page content remains unchanged, but the included file can be altered independently and, from the client perspective, and from edge caches such as Amazon Web Services' CloudFront, it's just one downloaded unit regardless.
