I had the same problem and I checked out the AVID/ARTIST-DISCUSSION-FORUM, where I found a solution, that is basically what Ollie already said, that worked for me:
1) Download Eucon 3.1 - not 3.12 - from euphonix.com
2) Uninstall eucon from your mac. The uninstaller can be found in your applications/Euphonix-folder
3) Repair disk permissions via disk utility.
5) Install eucon 3.1.
6) Right click on eucon icon in the applications folder, select "get info".
In the get info box, check the box next to "prevent app nap".
Close the panel, reboot the computer, and see if the lag persists.
For more info check:http://duc.avid.com/showthread.php?t=348994