Regardless, 7 MB/s on a stock 3000 over Zorro isn't too shabby, IMHO.
True.
The problem with adding accelerator RAM may be that CPU caching breaks data integrity. Since the CPU then lives on another bus apart from mainboard RAM it can't see (bus snooping) what addresses are written to by DMA - stale cache entries need to be invalidated.
This is not a problem which can't be solved (through proper OS and driver support or clever driver support w/o the OS) but it's unsolved on the Amiga afaik.
The only workaround is to turn off caches altogether (ouch) or flush caches after each DMA operation (a bit less painful but still). :-/
