From their site:

RPO runs on a web server applying performance optimizations to pages at runtime, just before the page is sent to the browser. RPO automatically implements many of the best practices from my book and YSlow, so the guys from Aptimize contacted me and showed me an early version. Here are the performance improvements RPO delivers:

• minifies, combines and compresses JavaScript files
• minifies, combines and compresses stylesheets
• combines images into CSS sprites
• inlines images inside the stylesheet
• turns on gzip compression
• sets far future Expires headers
• loads scripts asynchronously

I really like the idea of centralizing/standardizing many small optimizations and apply them server side.

It's pretty neat to be able to serve a highly optimized website without much efforts and development overhead. In fact, just not having to consider optimization is awesome.

On the other hand, I wonder how they deal with corner cases and if it's a realistic solution in term of robustness.

Debugging the web is not a trivial task and if the code is altered, automatically or not, between publications and execution there is always a chance that your code will break.

By example, if you forget a trailing ";" in your JavaScript it will break the minified version, but the development version will not yield any errors.

It's not so bad when you're working with one or two files, but with 10+ files clogged together .. good luck for finding which minified version breaks your production site.

Anyway, I guess I'll have give it a chance because I really like the idea of saving some time.