Since upgrading my iMac (i7 cpu) to the latest version of NAV (v7 or is it v12???) I noticed cyclic fan activity when doing nothing on the Mac. Further investigation showed that the fan activity was coupled with SymDaemon activity which was hammering the cpu at 390%, this appears to be across 4 of the 8 cores. I'm assuming this is related to the idle scan, but I don't have the knowledge to prove this.
Interestingly I've not yet seen the same behaviour on my MBP i7 or MBP core 2 duo, but there's still time I suppose!
All are running El Capitan 10.11.3.
Anyone else seeing similar issues?