Deactive components of Symfony2 full stack framework
You can build your custom symfony2 removing from your composer.json the line (and all you don't need as doctrine...)
symfony/symfonyand use only your preferred component, you can see the complete list from the github repo . As example you can configure simply:
"require": { "php": ">=5.3.3", "symfony/finder": "~2.3", "symfony/filesystem": "~2.3", "symfony/options-resolver": "~2.3", "symfony/framework-bundle": "~2.3"}, The documentation reference for the symfony2 components is here
Take care if you install a bundle that have in the dependences a module that you don't want it will download with him dependencies.
Hope this help.
PS: You should consider to use a microframework like silex