ANA 1.5 - CPU activity due to reverb

I noticed my CPU was showing an unusual level of activity with nothing playing. I removed all plugin instances and re-introduced ANA and the CPU load went back to zero. br
After playing one note on ANA the activity returned and remains constantly. CPU meter is dancing around with nothing playing. Seems to be related to the reverb, once I turned reverb off CPU activity dropped to
Mac Core i7 2.3 br
Logic Pro 9.1.8 32bitbr
OSX 10.8.2