I've noticed a couple of bug with regard to Jack and the new test build of Pd extended:
1) When connecting to Jack mode, Pd freezes and has to be force quit.
2) Another problem I've noticed is with current release of 0.40.3 extended, is when Pd is not computing audio, cpu usage shoots up around 30% .
This appears to happen when compute audio is first activated, then switched off. Switching on audio and cpu returns to nominal amount. This problem does not affect actual usage.
Specs problems appear on:
os 10.5.6 Intel 2.4 iMac
os 10.4.11 PPC 1 ghz
Jack OSX 0.81