Plugin language

[helios]

Okay, so here's what I need to do: I need to add plugin functionality to a program. The plugin will be used to process frames, kind of like a shader, but in software. So what I need is a language that can be embedded in C++ that's fast as hell, understands what a pointer is (preferably including pointer arithmetic), and is portable. If I can also get it to call C functions, even better.

I'm considering Python, since I've already done a little embedding with it, but I'm not sure about its performance.
Does anyone know of any other interpreter/virtual machine with these characteristics?

EDIT: Well, I know Python is out of the question. Just calling the function and iterating doing nothing exceeds my upper time limit by 13 ms. Actually doing some work takes 100 times longer than native code.

[helios]

I decided to go with native code and dynamic libraries. I have a question:
Is it safe for a DLL function to return pointers to other functions in the same DLL even if they weren't exported?

int cxxFunction(){
	return 4;
}

extern "C" __declspec(dllexport) void * __cdecl bureaucrat(void *a){
	return cxxFunction;
}

What about in UNIX?