Custom Property vs Client Tag

A window requires a large amount of data from a database, currently the data is being written to a client tag before opening the window and the window looks up the data from the tag. Every now and then values are displayed from the last time it was opened during the current session. Caching is set to never. My current theory is that the window opens before the tag write is complete, the first elements to bind get old values, later elements to bind get new values.

Would using a custom property instead of a client tag resolve this issue?

Is there any validity to my theory?