Hello! First of all, thank you for paying attention to your daughter and noticing that she is concerned! It sounds like you have been a positive influence on her for her to be so focused on achievement and for her to care so deeply about her performance! Based on what you've said here, I understand that you are concerned that she is overly stressed, though. I share your concern. People of all ages have meltdowns when they become overwhelmed with stress, and the negative consequences of those meltdowns can definitely have a ripple-effect into other areas of our lives.
For your daughter, the thing I would want to know FIRST is this: does she feel she has adequate healthy coping skills to manage the stress she is experiencing? Because, it doesn't really matter WHAT she is stressing on...what matters is how she deals with her stress when it threatens to overwhelm her. I'd like to know what, exactly, that she does when she is feeling stressed that helps her to feel better. If she has only unhealthy coping skills (for example, sleeping, shutting-down, raging, self-attack with critical self-talk, etc.), or only one or two healthy skills, we would want to teach her some additional healthy strategies to help her KNOW that she can cope.
Just one risk of not addressing this issue now could be that she may come to "learn" that stress is 'unbearable' which may cause her to turn to destructive or escapist strategies to avoid the discomfort, the pain of feeling hopeless, and/or the negative belief that she "cannot help herself." I definitely think it would be worth both your whiles to have her evaluated by her family doctor and/or a professional counselor. With a counselor specifically, she could learn the needed skills as well as be evaluated for other issues that may be contributing to the issue (for example, a learned belief that she "must be perfect or she is not worthy.") Plus, having a neutral support person to help her meet her personal goals is always a good thing. Good luck, mom and daughter!