Outlook runs incredibly slow and no memory to display calendar

Running Outlook 2016 and Windows 10. When I turn on the antispam plug in Outlook almost grinds to a halt. In addition when it does start up it does not allow me to look at some of the features. EG click on the calendar and it comes up with message that not enough memory available to display information. Switch off the pug in and everything is back to normal.

Any ideas how to solve this.