Concept 2.4 now available for download. As the main feature is the new JIT (sljit), and some basic code optimization (like dead-code elimination).
It almost tripled its speed since the first version with JIT. Here is an example for a basic benchmark for arrays + basic operations (lower the better):
About 6 times faster than PHP 5.4 and about the same speed with C (gcc, no optimizations).
I've also ran a Sieve benchmark (higher, the better):
The slight advantage for gcc comes from the fact that Concept core must call a function for accessing array elements, instead of a direct access (like in C/C++).
For now is fast enough for Concept to be a reasonable choice for CPU-intensive computations.
Average speed optimization for Concept/JIT is about 800%, but in some particular cases it is more than 2000%.