Where should one correctly include jQuery for Bootstrap 4 within Angular2, taking into consideration architecture best-practices and potentially performance when loading pages?
If you want to take into account "best-practices and potentially performance when loading pages" please, just don't use jQuery. If you are looking for usage of Bootstrap 4 components in Angular 2+ use a dedicated library that provide those without any need for jQuery, Bootstrap's JS etc.: https://ng-bootstrap.github.io/