From what I gather, threads-shared-memory has to be copied once when it is read, that alone will make it slower by a millisec or 2, in my guestimation. But I'm just an intuitive zen hacker, not a OS engineer.

If you have some bechmark code please post it. A "subjective" view of how fast something is, can be very deceiving when dealing with millisecond differences, since the human brain works at such a slow speed. So I will stand by what I said, since all books claim (with justification) that shared memory is the fastest form of IPC.

It is up to you to prove otherwise, since you challenge the conventional wisdom.

It is similar to the argument whether interpreted code runs as fast as compiled code..... if you put it on a 2Ghz machine, you can't tell the difference, but there is a minute one.

As far as shared memory being faster than a Berkeley Database, I think that is almost assured. How can calls to a disk-based database server be faster than reading directly from RAM? (Assuming a properly built system, and correctly written code)