We are looking to use in-memory tables for permanent and temporary tables used by T-SQL stored procedure based ETL pipeline. Goal is to fasten processing since it takes about 20 minutes for 10,000 users and it needs to be brought down to finish in under 5 minutes.

Is there a limit on how many rows you can have for in-memory tables for MS SQL Server? If there is no limit, is the any guideline on whether they become inefficient when large number of rows (hundreds of millions) are to be stored?

Have analyzed from available documentation but unable to get a firm answer.