@Susja Thank you for the ask again. I am glad that you are trying the ADS tool.
If my understanding is correct, you are looking for an extension that will monitor your database and troubleshoot slow running queries.
For lightweight query troubleshooting and basic monitoring in Azure Data Studio, I would recommend Azure SQL profiler.
Please do check out our documentation.
SQL Server Profiler extension (Preview)
Regards,
Oury