In a comprehensive head-to-head comparison between CircleCI and GitHub Actions, significant differences were found in their performance at enterprise scale, particularly in execution speed and queue management. Utilizing the React codebase and simulating a high-throughput environment typical of modern enterprises, CircleCI demonstrated a substantial speed advantage, executing pipelines 40.29% faster than GitHub Actions' default runners and maintaining a 2.09% lead even against more powerful GitHub runners. This speed translates to significant time savings for developers, potentially reclaiming hundreds of engineering hours each month. Moreover, CircleCI excelled in queue management, efficiently utilizing its full concurrent capacity to handle up to 500 jobs simultaneously, whereas GitHub Actions faced considerable limitations, with median queue times exceeding 153 seconds and maximum waits extending beyond 63 minutes. These findings suggest that CircleCI's superior architecture can lead to improved development velocity and reduced infrastructure costs, making it a more effective choice for growing engineering organizations focused on optimizing CI/CD performance at scale.