S3Cache creates a new fragment cache filestore using Amazon's Simple Storage Service (S3). Instead of your fragment caches stored at say '#{RAILS_ROOT}/cache', your cache can now be located at one of your S3 buckets.

S3Cache also extends ActionView Helpers by adding a new cache helper called 'cache_xml'. This caches xml and rss files at S3. Your rss feed can then be accessed at something like http://steveodom.s3.amazonaws.com/feeds/my_feed.rss.

My main goal is writing this plugin was to offload my xml and rss feeds to S3. For fragments within one of your existing rails pages, there is definitely a performance consideration for caching your fragments at S3 instead of your own server. It is just not as fast passing bits over the internet as it is keeping it all on your own server. Having said that, I have found the performance of my rails pages with cached fragments stored at S3 to be acceptable. It is a little slower, but not so much where most site visitors will even know the difference.