I'm upgrading from LabView 8 to LabView 2014 and have the same problems, also using Linux/Ubuntu to run my application.
I found this article:
https://forums.ni.com/t5/LabVIEW/CPU-usage-rises-in-LabVIEW-executable/td-p/2194414
In my case it doesn't help to replace all the deprecated property nodes, but I think that's one problem relying to the high cpu load...