16-bit Zorro memory will only slow the system (relative to 32-bit accelerator memory) if the acclerator memory is depleted. 16-bit memory relative to no accelerator to begin with is, of course, faster (slightly). That's why it's called Fast RAM.
Your best bet for performance is to grab 3 more custom GVP SIMMs for the accelerator.
Plugging in all those Zorro boards will overload the bus (8MB maximum). Since you already have SCSI on the accelerator, I'd suggest using only the 8up card in the interim.
