After the athlete finished the race, a reporter comes up and asks a question. Which one is better?
What are you saying to your performance?
What do you say to your performance?
In American English, neither version is correct. Normally, one says something about a topic, and/or to an audience. The following versions are grammatically correct, but only the second one fits the context:
1b. What are you saying about your performance?
2b. What do you have to say about your performance?
2b references the idiom "have your say", and directly asks the athlete to say something about his (or her) performance.
1b is one level more "meta" than 2b. Once the athlete has said something about his (or her) performance, then it might make sense to ask about what he (or she) is saying. For example, advertisements for a movie might ask, "What are people saying about The Hot New Movie?" These ads might quote movie reviewers saying things like "Two Thumbs Up!" and "Awesome!"
An exception: Sometimes Americans say "what do you say to" instead of "how do you respond to".
The following dialog is grammatically correct in American English:
What do you have to say about your performance?
Well, I started off slow, but I never gave up. I focused on finishing strong.
You have a lot of fans here today. What do you have to say to them?
It's great to perform for an enthusiastic crowd.
Nass T. Kritick said your starting technique is poor. What do you say to that?
I don't worry about critics. I just do the best I can, every time.
The difference between the continuous tense and the indefinite tense is that the former expresses the immediate action, taking place now, whereas the latter expresses the usual action that can take place is similar circumstances. We all know that, I suppose.
When the reporter asks his question using the first form ("What are you saying"), the expectation is that the athlete will give an account of how his/her performance in the race just run differs from other accomplishments of the same athlete, how this race was special or perhaps singular.
When the reporter asks the question using the second form ("What do you say"), the expected response is of more general nature. The reporter uses this form to suggest that the spectators would want to hear the athlete share his/her views on the race just run, like an athlete usually would, when asked about it immediately after the finish.
As to which form of the question to prefer, I am not sure. The "what are you saying" does not sound/look usual (but perhaps I don't watch enough sport shows), since it suggests that the athlete is saying something. I'd probably use the second form.