Unfortunately, there really isn’t a way to make some things go faster.
If you’re talking about the field group editor, This shouldn’t get too slow. Each “Field” in the field group is a “Post” so it can take some time to load them and save them.
If you’re talking about the speed when editing a post, this is something that you’ll need to account for. Loading is not generally a problem, but saving can be a problem. You will find other topics on this. ACF uses the standard WP functions for saving meta data. This means that every field adds additional db queries. With enough data the admin page for a post will eventually time out.
