Running on 2 Cpu Opteron using netperf loopback mode shows that the change is
very small when averaged over 10 runs. Overall there is 
a .28% decrease in CPU usage and a .96% loss in throughput.  But both those
values are less than twice standard deviation which was .4% for the CPU measurements
and .8% for the performance measurements.  I can't see it as a worth
bothering unless there is some big money benchmark on the line, in which case
it would make more sense to look at other optimizations of the loopback
path.

Opteron has no problems with indirect calls, IA64 seems to be different
though.

But when you see noticeable differences even on a Opteron I find
it somewhat worrying.

-Andi