Firebird 2.0 took what, 4 years? In that time, SMP went from a mildly
exotic high end feature to a cheap, common server feature, to, with the
advent of multi-core, a near universal feature on all but the very
cheapest boxes. In fact, during the time that Firebird 2.0 was
slipping, dual cores were conceived, designed, implemented, and
shipped. Happily, Firebird 2.0 did ship before production quantities of
quad-cores. But, after all these years, the production releases of
Firebird is a) compute bound, and b) incapable of exploiting more than
one processor.

SMP support is a two-times performance kicker on a two core system and
nearly a four-times kicker on a four core system. If there any
conceivable feature in the 2.x pipeline that can deliver a 2X or 4X
performance boost?

Rather than loading Firebird 2.x with dozens of individually
insignificant features (IN LIST, for example), would it not make more
sense to get the Vulcan based code base to product status and out the door?