If this is a fresh install, this probably doesn’t apply, but may if it was previously installed and you are only now using it seriously. Just as a general rule for browsers and computing, clearing cache or temp files often resolves issues with hanging. Sometimes stale data leaves the system to time-out waiting for information that can never arrive.
In Firefox, it’s the “Cache” check box in Settings | History | Clear Recent History… Be sure that “Everything” is the time range in the box at the top and that no other boxes are checked unless you want them to be.
