We have multiple Sharepoint site collections and sites on a SharePoint 2013 farm.
Recently we have noticed a couple of issues with the workflows on the farm.
The workflows are very slow to process. Sometimes it takes 20 to 30 minutes to process a workflow step.
The workflows that send an email ofter send multiple copies of the same email, sometimes up to 100 or more times.
The workflows were working with no issues until recently (probably 3 weeks ago)