Have you tried creating a new template?

Highlight and copy all but the last paragraph mark in the original template. Paste to a new template and see if that makes a difference. If there is corruption in the original template, it is stored in the last paragraph mark.

Not knowing how the original was set up makes it difficult to say why documents are slow to open. It may have macros, fields, or other automation in it that is glitching on your system.

You are okay if the folder path is correctly set in File Locations.