High CPU when debugging

Using PyCharm pro 2016.1 - often (not always) when debugging does PyCharm spin up the CPU like no tomorrow. Killing/exiting/stopping the debug session always seems to quiet things down again.  Occasionally I have high CPU cycles when starting up PyCharm, generally it stops after some time, sometimes I have to kill the session.

Whats up with this? This is really affecting my workflow.