Expedia Group's journey to implement GitOps with ArgoCD is a story of innovation, scalability, and overcoming challenges. Our GitOps journey involved migrating from KubeFed to ArgoCD, focusing on extensive scalability testing across hundreds of virtual clusters, set up using open source tool, vcluster. We proactively identified potential challenges and prepared comprehensive test cases tailored to different application flavors. We created three types of applications for testing, with sizes varying between 15-30 resources, including CRDs & jobs, small apps containing 15 resources and large applications containing 30 resources. We experimented with multiple test scenarios, using permutation and combination of applications tested on 300 vclusters, scaling 1,000 applications to 30,000+ across these clusters. We concluded this initiative with determining optimal settings for various tunable parameters in the ArgoCD controllers.