From: Thomas Graf <tgraf@suug.ch>
Date: Wed, 6 Jul 2005 01:41:04 +0200

I still think we can fix this performance issue without manually
unrolling the loop or we should at least try to. In the end gcc
should notice the constant part of the loop and move it out so
basically the only difference should the additional prio++ and
possibly a failing branch prediction.

But the branch prediction is where I personally think a lot
of the lossage is coming from.  These can cost upwards of 20
or 30 processor cycles, easily.  That's getting close to the
cost of a L2 cache miss.

I see the difficulties with this change now, why don't we revisit
this some time in the future?