Apart from using our site to determine this, you can always scroll down the casino website and see where they are licensed. MGA (being Malta) license is a good sign, Curacao is not that great, but acceptable.
Be vary of sites that do not show any licensing info or claim to have a license in places like Antigua or Costa Rica.
In the end, even licensed sites could slow pay and no license sites pay very fast. It's all about doing some research about the casinos reputation in the community.
BitStarz is the fastest paying casino we've reviewed on our site.