  GitHub Copilot is an artificially intelligent programming assistant used by
many developers. While a few studies have evaluated the security risks of using
Copilot, there has not been any study to show if it aids developers in
producing code with better runtime performance. We evaluate the runtime
performance of code produced when developers use GitHub Copilot versus when
they do not. To this end, we conducted a user study with 32 participants where
each participant solved two C++ programming problems, one with Copilot and the
other without it and measured the runtime performance of the participants'
solutions on our test data. Our results suggest that using Copilot may produce
code with a significantly slower runtime performance.
