For those concerned that we won't be able to compute rapidly all that we need to, here are some good news. Project Jacuzzi:
The project delivers Java™-bindings for CUDA. CUDA is a framework by NVIDIA which enables a programmer to use the graphics processing unit (GPU) of a computer for scientific computations or image processing. The current project state is alpha but it might however be useful for you. Browse the javadoc documentation to find out. Everybody is invited to contribute.
That should bring up the immense power of GPGPU (also on wikipedia), and stream processing, even from (slow) java.
We shouldn't worry about such problems now. Maybe in an year or so.