This is just the basics. Much more is still to be completed (such as the CLI layer, code generators, main configuration etc).
The switch to using shared components with Symfony is a learning curve, but the benefits outweigh the difficulties. Having a well-tested and debugged set of components for routing and other components means that we can focus on what Scorpio needs. There is some overlap (translation, config etc) but where it makes sense using the third party libraries via Packagist and Composer should make getting up and running that much easier.
In terms of performance, already there are substantial gains. Ad-hoc testing with Apache bench in a totally unscientific manner on an Intel i7-860 running Kubuntu resulted in over 300 requests per second without real performance tuning and running through Smarty with translations and sessions enabled.
It is still early days and changes still need to be made: Scorpio2 is based on Symfony 2.1 which is still under development, so as it changes Scorpio2s base will change.
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