Pantheon, a leading WebOps platform provider, faced significant performance challenges while scaling its engineering team from 60 to 200 members and dealing with a complex legacy codebase. To tackle issues like a 10-12 second load time on their dashboard, the company adopted Replay, a developer tool that enabled them to diagnose performance bottlenecks and bugs effectively by providing detailed insights into the code's behavior. This adoption allowed Pantheon to improve load times by 500%, reduce the mean time to resolve bugs from weeks to days, and accelerate new engineer onboarding. Replay's ability to visualize and pinpoint code issues facilitated a strategic shift in priorities, contributing to a more efficient development process. The seamless integration of Replay into Pantheon's workflow not only enhanced performance but also empowered the engineering team to focus on building rather than debugging, aligning with Pantheon’s mission to deliver agile and scalable web solutions.