Yes, the packages have been tested, and Ubuntu MATE for Raspberry Pi is not, generally speaking, well optimized. It seems heavy and slow, the load average on this system for 15 minutes period indicates 2.33 cpu utilization without NoMachine even installed and the system being idle! (maybe except for using htop).
We have published results of what works best. You can see them here:
https://www.nomachine.com/AR03M00842
Right now, until MATE is optimized to run more efficiently, changing the system you are using for something more likely to work with much lesser CPU loads (e.g Raspbian when running NoMachine Client indicates about 1.7 average cpu utilization) is the best way forward.
We are investigating ways to allow NoMachine to install on all devices and their OS flavours. As more are added, we’ll update the notes. As for the Odroid c1, it’s on our to-do list of devices to test.