I'd like to tell you a little success story about using sfOptimizerPlugin. I did many things in my "public" application to optimize performance [and end up having] an average execution time of ~150ms per page, wich leads to ~100ms in the production environment. A little bit slow, I think.

After [installing the plugin and] running $php symfony optimize public staging over the environment, the execution time was reduced by 50ms from ~150ms down to ~90ms, nice. And even the production environment acts faster now, with only ~30ms to serve pages, very nice - 70% faster!

He even suggests using the sfOptimizerPlugin in a cron job on a server to help keep things constantly optimized.