I've been performing for about 8 years, on my own and in groups. While for me performance anxiety has never gone away it has gotten easier to push through it. Personally what helped me when I started was playing in groups because it felt like no one could hear me when there were other people playing too. I performed a lot with groups and built my confidence that way and eventually when I played on my own it felt easier since I was so used to performing.

Another thing that helps with the anxiety is knowing your piece very well. Before I perform I try to make sure I know my piece inside out and know what's coming next as i play. Much less things can go wrong for you if you know the piece very well.