I posted about this a few back. I have been running this now for about a week and there are some issues, but they are being sorted out according to the support team at FutureGlue.
It seemed much worse when I was in Outlook Cached Exchange mode, but the leak still happens.
I believe they thought this was fixed in the current release, but unfortunately not. I can say that once this leak is sorted, this will be the perfect addon!