I completed a simple 8-bit x 8-bit multiply function (iterative adds).  I decided to do a quick benchmark to check its performance.  Since this is an iterative add function, the worst case is FF x FF.  It takes 1.61ms to perform with the clock running at 12MHz.  So it takes 19,397 clock cycles to perform the operation.  That's a lot of moving.  If there's 256 loops, then it takes about 76 clocks per loop.  There's currently 3 clocks per instruction, so about 25 instructions per loop.  That sounds about right.  

A better algorithm would speed this up like the shift-and-add algorithm (probably).  But it's good to get a baseline.  The number of loops is really the killer.  A shift-and-add algorithm does I think 8 loops with an add and a shift right each loop.  Of course, in the best case, my algorithm takes zero loops, so it's possible to be faster, but statistically I'm sure it's slower.

But now I can store this function in the ROM and call it whenever I need to do a multiply.  However, I have it pointing at dedicated memory locations.  I need to work on using the stack to pass values to functions instead.