AVR-Chat

I have an application which needs to store 256 bytes of data. My
current (C) solution is way too slow. Could anyone point me to the
fastest way to go about reading a fixe number of bytes into an
array/memory location using assembler? ie how can I replace the loop
below most efficiently.

char mydata[256];
void myloop()
    {
    for(d=256;d;d--) mydata[d]=PIND;
    }

many thanks

Ken