Hamlet is a flawed character. Which of his flaws can be considered the tragic flaw that leads to his downfall?

Shakespeare's character Hamlet possesses considerable indecisiveness and procrastination. Given his father's murder, his mother's marriage to his uncle, the sight of his father's ghost who wishes him to take revenge and Ophelia's suicide, Hamlet postpones his intentions to take action in each situation. As a consequence, his reluctance and hesitation, which are probably due to his education and refinement of spirit, finally lead to his tragic end.