I got a rough benchmark.
Main purpose is to know how Cloud Files(rackspacecloud.com) is fast from Tokyo, Japan. Also I compared the speed with Amazon EC2/CloudFront and Sakura Internet 7,800yen dedicated hosting service.
% ab -n 50 -c 5 http://server/image-file(jpg/png/gif)
Transfer rate (Kbytes/sec):
1527 (www.google.com)
1245 (s3.amazonaws.com)
3796 (cloudfront.net)
45 (sakura internet 7800yen server)
2135 (cdn.cloudfiles.rackspacecloud.com)
42 (rackspacecloud cloud server mem 256M)
@San Jose, CA (3.2Mb/s by speedtest.net)
1558 (www.google.com)
381 (s3.amazonaws.com)
3753 (cloudfront.net)
304 (sakura internet 7800yen server)
2058 (cdn.cloudfiles.rackspacecloud.com)
@Tokyo, Japan (35.4Mb/s by speedtest.net)
Cloud File is pretty good. Indeed, Cloud Servers plan is good at low-end scale-up. Never change its IP to resize 256M memory to 512M. There is a down time like a couple of minutes. Unfortunately, DirectoryIndex (like index.html) doesn’t work on Cloud Files just like S3/CloudFront.
ref) AmazonS3上のファイルを国内でも高速配信可能なAmazon CloudFrontリリース — Media Technology Labs