Of course, we do not know the details of the project that you did or what your role was. Therefore, we cannot know exactly what you could have done to improve your team's performance. What we can do is to point out general ways in which a team leader (since you have put this under Leadership, I assume you were the team leader) can improve team performance.
First, you might think about how well you did on assigning tasks to people. Did you give each team member a task that he or she could be good at? Did you give them the right amount of responsibility, not overwhelming them with things they couldn't do or boring them with tasks that were too easy?
Second, you might think about how well you motivated your team. Did you treat them in ways that would generally make them likely to want to work hard? Were you supportive enough of people having problems? Were you tough when you needed to be?
Finally, did you make the right decisions when called upon? When your team needed guidance, were you able to provide it? Did you make clear decisions and communicate them to your team?
All of these are areas in which a team leader can influence a team's performance.