i use Jamin with ardour as an insert in the master postfader. Jamin takes around 95% cpu usage and an export needs from 2 to 40! Minutes.
The system specs are:
Ardour 2.7.1
Jack 0.116.1 (checked other versions but without a solution)
Archlinux with 2.6.28 stockkernel
cpu x86_64 Amd dualcore.
ok, than fire up qjack and as soon it shows that jackd has started stop it via qjack again. if now you open the ‘messeges’ window of qjack and scroll a little bit to the top, you will see the command qjack was using for starting jackd.