Current situation: We have a SP farm (2016) with only 2 servers (app and database). It has 30 site collections and each collection cca 25 document libraries. Total amount of data in these site collections (in a single content db) is around 700 GB. And we use SharePoint 2013 workflows.
Problem: Lately, users experience enormous degradation of performance when they start workflows or try to upload documents. And it doesn't happen every day, there are days when everything works fine.
I don't see any problems on application server, so my doubt is the database. We haven't found any limitations on allowed number of workflows on the SP server, currently, but we have 90000 sharepoint 2013 workflows that are still in "Started" state. Could that number of running workflows be the problem?