[iroxmxinau]

I have found that quick or fast tempo can be slowed by extremely loose grip pressure. This will ease the tension on your forearms and shoulders thereby freeing up your swing. Your tempo will slow a bit but the main point is a free swing.
There is nothing wrong with quick tempo provided you take away tension. If I had to guess your tempo is quick almost all of the time bit when you play well it's devoid tension.