Static assets for the platform UI are loaded using the _ezcombo -route. This currently uses the regular Kernel and loads quite a bit of unnecessary things, including the current user and more. With clear caches in development environment this means that it takes somewhere between 4 to 5 seconds to load 30 static files. Symfony perf debug attached.

This destroys the development experience as caches are frequently purged completely and the UI is left pending. With subsequent requests this goes down to some ~750 ms, which is better but still an enormous overhead for concatenation of 30 files into one.

I think the current setup defeats the purpose of the concatenation performance benefit (especially in development) and should be improved upon. Without a complete refactoring to keep it feasible and provide results quick.

Maybe the easiest way forward is to create a separate Front Controller and Kernel for _ezcombo that have the minimum overhead - can also be a Symfony MicroKernel as Symfony 2.8 is in use.

The controller and relevant core code are:

• https://github.com/ezsystems/PlatformUIBundle/blob/master/Controller/PlatformUIController.php
• https://github.com/ezsystems/PlatformUIBundle/blob/master/Loader/ComboLoader.php