All functions are inline table valued function but there is a couple of sub function in waterfall inside of each functions, (all inline table valued function), maybe this is the problem.

I being using function because of the ease of work with filters of the query, I think I can use temporal table directly from the application I’m developing instead of put all in just one function.

Or reading the article http://sqlinthewild.co.za/index.php/2008/08/12/views-or-functions/ I gone a try use a stored procedure too, the think is that the information is used in a Crystal Report and I never tray to use a stored procedure as a source I don’t know if is possible.

If is this is helpful I attach the execution plan in the replay.