Using JACK makes the Frinika experience on Linux much more enjoyable - and I've managed to push my 1.5 GHz Centrino laptop from 2006 down to 5 milliseconds latency.
For this to work you should run JACK in realtime mode and 128 frames. Also you must make sure that Frinika is able to go realtime.
Make sure you're member of the audio group (check /etc/groups)
and then edit /etc/security/limits.conf
and add these lines:
@realtime - rtprio 99 @realtime - memlock unlimited
(as described here)
Also remember to turn off any CPU frequency auto-scaling - as this will only cause disturbances.
Start Jack before you start Frinika - and Frinika will connect automatically to Jack.