Gambling with TOR feels like gambling with super slow speed. We know TOR throttles our speed, and you won’t get anywhere near the max--probably not even 5mbps. So, it’s not ideal for casino games that need a high-speed connection. Plus, if gambling is restricted in your country, using TOR is risky since it could lead to your funds being frozen.
You are right, it's very slow when you gamble with TOR, it throttle speeds because it has to go to several hops. And usually those resides somewhere in EU and so it really are going to be very slow rerouting your connection to those countries. But if you like your privacy, then TOR is the best services to used, but not in gambling.
And besides, majority of the casinos doesn't want their customers to used TOR and so if the casino caught you or at least found out that something is not right with your connection, then maybe you will get ban or push a KYC to see where you are really from.