Suggestion,let us get posts with this tag by id

and exclude posts from these tags by id too,not to load the entire tags on a list.

Hello,aldolat

The reason is that if we have a huge amount of tags,then it will be a concern to us everytime the plugin has to load all of them when we try to set it.It might be a problem,right?

As for category,I think no one will try to create way too many categories at all since it makes no sense and wordpress itself is not designed for that.But tag does,you can see there is no all of tags shown up on wordpress post editing.

https://wordpress.org/plugins/posts-in-sidebar/