Unfortunately, the only other processor card upgrade for the Amiga 500 (which is a vast speed improvement over the Derringer) is a PP&S 040 which are extremely rare. And, I'd have to sacrifice 24MB of Ram (Derringer can use up to 32Megs while the PP&S can only use 8MB)
I guess I want to try to tweak out as much speed as I can from this computer.