ROOT6: a quest for performance

The sixth release cycle of ROOT is characterised by a radical modernisation in
the core software technologies the tookit relies on: language standard,
interpreter, hardware exploitation mechanisms.
If on the one hand, the change offered the opportunity of consolidating the
existing codebase, in presence of such innovations, maintaing the balance
between full backward compatibility and software performance was not easy.
In this contribution we review the challenges and the solutions identified and
implemented in the area of CPU and memory consumption as well as I/O
capabilities in terms of patterns.
Moreover, we present some of the new ROOT components which are offered to the
users to improve the performance of third party applications.