Contao is a content management system (CMS) which is mostly used in the DACH area. One of the developers there profiled the system with blackfire.io (a profiler from the guys that brought us Symfony).
Long story short, he found a single line of code that (depending on the size of the installation and number of extensions) led to 50ms to 100ms more for every single call.
The blackfire.io guys even wrote there own blog post about the discovery.
Two things I take from this:
- Profiling with blackfire.io seems to be really good
- When choosing a CMS consider what framework they use as basis for it. There are still systems out there that want to invent the weel over and over again. The chance that those contain bugs like the one found there is way higher.