If you experience issues on Omni 6 on hammerhead, there is a missing file in /vendor/lib that causes runtime linking failures for /system/bin/thermal-engine-hh.
As a result, your system won't be doing thermal management properly and will feel laggy and possibly unstable.
All recent hammerhead omni builds (last checked on 2016-03-14) are missing the /system/vendor/lib/libthermalioctl.so library that is needed for thermal-engine-hh to work properly.
How to find if you are affected?
init: Starting service 'thermal-engine'... init: Service 'thermal-engine' (pid 8456) exited with status 1 init: Service 'thermal-engine' (pid 8456) killing any children in process group
I've opened an issue on the Omni Jira: http://jira.omnirom.org/browse/OMNI-1286
In the meantime, you can drop a recent /system/vendor/lib/libthermalioctl.so from CM13 or the stock ROM to make everything dandy again.