RE: Performance issue in D365 F&O
Can you describe more details about the issues that you are facing? Also, is this a cloud system or on-premises?
1. Also batch jobs are run in user sessions, so if you have batch jobs running, then the users who set up the jobs will show up in Online users
2. This question is so far too general, please provide more details about your problems.
Did you check Environment monitoring in LCS? You can use that to get some details about possible issues and bottlenecks, such as long running queries.
You should also discuss with Microsoft. If you are in the FastTrack program, you can reach out to your FastTrack solution architect. Otherwise you can create a support request. Did you provide accurate information in the Subscription estimator Excel before golive? The prod system is sized based on the figures that you provided in that document.