In 2009’s “Rearview Mirrors,” Geoff Johns may have given us the definitive answer to this question. When Barry Allen returned from the dead after dying in Crisis on Infinite Earths, the Speed Force was all out of whack. Believing that his very existence was harming his fellow speedsters, Barry decided to sacrifice his life to the Speed Force in order to restore balance to the universe. Before he could go through with his plan, Superman caught up to him and urged his friend to reconsider. During their conversation Superman claimed that he’d even won some of their races over the years, but Barry responded with a mic drop. “Those were for charity, Clark,” Barry uttered to a stunned Superman before leaving the Last Son of Krypton in the dust and running into another plane of existence.”
Source: nerdist.com, The Flash Rebirth #3 (2009)