Inspired by GZipFilter, I have created a new compressing filter. I hope it addresses the performance, internationalization, and Servlet-2.3-container-forwarding issues that people have raised about this filter.
It is open-source and written from the ground up for performance -- it will not compress tiny responses, and will not buffer the entire response into memory. It handles HTTP headers correctly (esp. "Vary", and encoding headers). It also supports more compression algorithms, and adds features like logging and compression stats.
Please give it a try, especially if you are having issues with this filter!
PJL Compressing Filter