Q: bluetooth mouse and keyboard hesitating

Ever since I did the latest security updated on my new MacBook Pro (15" retina display), there is a hesitation in my BT Apple mouse and keyboard.  Becomes unresponsive about every 2 seconds for about a second.  Have tried turning off, removing and repairing devices.  No change.  Have rebooted MBP (hot and cold).  No change.  Have a Dell monitor set up to mirror my laptop screen.  Tried turning it off and disconnecting it.  No change.

Any ideas on what could be causing this intermittent BT connectivity?  I think it is a result of the recent security update because it started immediately after rebooting after the update.