Response to: Parallel.For and simlilar ..concern that it is optimal

Revision 1
As a .NET solution, the Microsoft parallel library is very good one. As a general library it is one-for-all-size and not tailor-made, so there should be scenarios where it will under-perform...
If you look for the better performance some C/C++ code will probably serve you better...
It is also possible that you can build your own .NET library that performs better for your special case, than the built in methods...
In any case it is very important that you learn how parallelism works on the CPU/OS/Framework level and how your chosen library implements all that...
CPU:
http://en.wikipedia.org/wiki/Parallel_computing[^]
http://blogs.msdn.com/b/karchworld_identity/archive/2011/04/01/cpu-parallelism-techinques-of-processor-optimization.aspx[^]
OS:
http://en.wikipedia.org/wiki/Computer_multitasking[^]
http://en.wikipedia.org/wiki/Thread_(computing)[^]
Framework:
http://msdn.microsoft.com/en-us/library/ff963553.aspx[^]

And with Google you can find much mire sources to read...