Personally I've experienced this - where my performance anxiety overall went down after practicing improvisation regularly - so I wasn't surprised when Nancy reported:
Her stage fright's basically gone.
A little bit of adrenaline I think helps us perform well, but when our anxiety goes through the roof it can ruin a performance.
If you had to rate your performance anxiety on a 0-10... and 0 is nothing, 10 is a full-blown panic attack, where are you at in your performance journey?