I just checked it, and I was able to connect to an external database hosting service (JawsDB) from a free hosting account.
If you are unable to connect to the external database you’re trying to connect to, please verify that the database you’re connecting to allows connections from remote servers, and has whitelisted our server IP addresses for access. Remember, many web hosting providers don’t allow Remote MySQL access by default. Some don’t allow it at all, and some require you to enable it and setup whitelists first.
This seems to be a restriction with your external database host, not with our servers. And this is definitely not some evil scam to force you to upgrade.
That said, the website loading very slowly is to be expected when you’re using a database at an external provider. MySQL (especially when used from PHP) is extremely sensitive to latency. Remember that this latency is added to every query executed from your code. So if you have a latency of a few dozen milliseconds, this can easily stack up to a second or more on the full page load time.