Performance is an essential part of the learning process. It helps us all understand that sometimes we have to just give it a go and see how we fare using the skill we have so diligently practised.
It also tells us what we need to practise - the mistakes we make during performance reveal what elements of our practise have really sunk in and which ones need more work.
During performance we have to rely on muscle memory to guide our fingers into the right places as we try to focus our energies on the music itself.
Forget all the rules of practise and keep going no matter what - it doesn't really matter whether you are playing publicly in a band or recording yourself playing to a backing track - you'll still need to remember your parts, play in time and follow the music until the music is ready to stop.
Performance is about playing something all the way through and ignoring any mistakes you make along the way.
An audience expects, at the very least that the music makes some sense - that it has some form that they recognise and can connect with.