One of the major issue with WP is two slow. projet: - no

Hi,

One of the major issue with WP is two slow.

projet:
- no use of blog / posts
- use of front only 10 pages about service infomation etc.

- created custom post type with own write plugin with function and custom fields with acf.

- site member have to login and add,edit, record in custom post type crud model.

- user will have only profile and custom post type menu access from backend.

To less burden on wp loading. I reduced plugins and all custom function put in file.

Still wp-admin is too slow loading,
even there in not a single member ( as testing phase )

as if member increase then this will be major issue.

So any one in wpmy Advance Developer , please advice me programically , how can i achieve best optimum result of wp OR

in this project use case , what flow can be adopt with with WP.

Regards,