Using MS SQL Express for smaller project for Orchestrator but started becoming unresponsive after using for a year


We bumped into issue where Orchestrator not responding and robots keep on getting unresponsive on our Orchestrator two weeks ago. We were unsure what was causing this issue for a while then found out that MS SQL Express was doing the bad.
We know that MS SQL Express is not recommended by UiPath but I do see lots of people using it as I learned in the Forum.
We deleted the visible and known log on database, deleted unwanted users from Orchestrator, and tried everything we can think of but it did not solve the issue.
We even moved the Orchestrator to different machine hoping that will make a difference, but it did not change.

I am wondering what triggered the issue and what was the cause of unresponsiveness (the problem here is that Orchestrator was not all the time unresponsive, it often became unresponsive when more than three people access Orchestrator at a time).
Has anyone experienced this? If so, do you know what was the cause of it? And how you soled it? If you have any temporary relief plan, what did you do?

I appreciate for your knowledge and the advise.
Thank you!