I am seeing the same thing with version 2.3.0.151 and Yosemite 10.10.5. Adobe CEF Helper is using a consistent 20-30% cpu while no adobe apps are running and haven't touched anything in the cloud files. Fusion is running a whole other virtual Mac in the background and is only using 2-3% cpu, Dropbox is showing 0.1-1% cpu while idle. Please test this stuff with your desktops before you consume our resources Adobe!
Turned off file sync and it didn't seem to change. Exited CC and started CC and high cpu seems to have cleared, but I'll bet it is back tomorrow.