On the Lakion blog there's a recent post sharing how they used the Blackfire.io profiling service to [speed up their application's tests] (Behat)(http://lakion.com/blog/how-did-we-speed-up-sylius-behat-suite-with-blackfire) and find the "pain points" to fix.

Feedback time is one of the most crucial factors during development and the red - green - refactor cycle. In case of Sylius, the full build used to take two and a half hour, including 55 minutes for only PHP 5.6 jobs. Waiting so long for feedback is not an option for a project of this size and with so many active contributors. As much as I am Xdebug fan, I have never really used it for profiling - the snapshots generation was slowing down the profiled script significantly and resulted in monstrous files, which weren't easy to read.

Half a year after I have first heard of blackfire.io I decided to give it a try. It resulted in a series of pull requests that speeds up Sylius test suites 6 times and reduces memory usage to one tenth.

They go through some of the major bottlenecks that the service helped them locate including:

• an issue with the login process and their role evaluation handling
• problems with time spent doing router initialization
• Doctrine performance issues running it without a class metadata cache

For each item they describe what the service was reporting and how they corrected it in the application. Most of the changes were relatively small, fortunately. They also link to the results from before and after the changes so you can see the difference. As their environment is Symfony-based they end the post with some other helpful Symfony tips to getting the most out of your application and enhancing its performance in a few simple ways.