DSP is one domain where performance of a tiny part of the code (say 1%) is far, far more important than everything else. If you need to apply a filter to remove high frequencies, or if you need a Fourier transform, no high-level tuning or special algorithm will cut it: you need the filter or the transform, even if it's very costly. The bottleneck is real and unavoidable.
I work in data acquisition and in this domain C/C++ is king. The raw number-crunching is essential (for our applications anyway), and any bonus that can be had from SSE operations, cache locality, loop unrolling, software pipelining, etc. can have a major impact on the overall performance. Assembly is still common on DSP processors and the like (they typically provide a special instruction set). Even in C++, we tend to use the bit-twiddling and pig disgusting optimization hacks that low-level access provides :)
Some people use higher level tools such as LabView but the performance is a huge step down. It's OK for prototyping and learning.
No. Objective C isn't performance oriented, and while it's fine for most desktop apps (!) it's not in the same league as C++. C++ can actually let you use higher level structures that are faster than in C or Objective C because of template meta programming, as shown in the Blitz template library for numerical computation.
http://www.oonumerics.org/blitz/
This is what Templates are made for. And this is what you can't do in something like Java or Objective C. Java Generics boiling down to type cast at run time to and from Object, it doesn't help performance a bit.
I work in data acquisition and in this domain C/C++ is king. The raw number-crunching is essential (for our applications anyway), and any bonus that can be had from SSE operations, cache locality, loop unrolling, software pipelining, etc. can have a major impact on the overall performance. Assembly is still common on DSP processors and the like (they typically provide a special instruction set). Even in C++, we tend to use the bit-twiddling and pig disgusting optimization hacks that low-level access provides :)
Some people use higher level tools such as LabView but the performance is a huge step down. It's OK for prototyping and learning.