Popup Pro Plugin causes backend to be VERY slow

We discovered that popup pro is causing our backend to be incredibly slow and there are lots of errors from the plugin in our error logs. We know it's the plugin, because we cloned our install of treatsie.com to testreatsie.wpengine.com and then disabled the plugin on one of them and it resolved the long lag in load time. We like the plugin, but can't keep using if it adds 10 seconds to the load of a page. Please advise.