Thanks for the question.
No, it does not use any API for SSL checking operations. The script depends on your own server for checking SSL (by trying opening a secure socket connection to the queried domains' server through port 443).
So it should be fast as before if your server performance remains the same.
Hope that answers your query.
If you have any questions, please create a ticket in https://support.devslib.com/
Or make a new comment on this Codester Support page (replying to other user comments will send notifications to the main commentator which might be annoying to them).