There is a fundamental difference between practice and performance. You should never get them confused. Practice is preparation. Performance is action. Practice is where you improve. Performance is where you execute. When practicing, you are working outside your abilities. When performing, you are working within your abilities. Think of it like a box. The box is your ability. When practicing, you are working outside the confines of that box so that you can, hopefully, increase the parameters with time. When performing, you are working entirely inside the confines of that box so that you can execute at your best and highest ability. The difference is very subtle but it exists and shouldn't be taken lightly. Practice is where you expand what you know. Performance is where you apply what you know.