GitHub underwent significant architectural changes to enhance speed and scalability following its migration to Rackspace. The updated architecture involves using HTTP, SSH, and Git protocols to handle user requests, with a focus on efficient load balancing and server management. The infrastructure includes Xen instances for load balancing, bare metal servers for front-end operations, and a sophisticated database setup with MySQL replication. The system also incorporates a unique approach to Git repository data retrieval through a service called Smoke, which uses a custom routing proxy, ProxyMachine, and a proprietary library, Chimney, for efficient file server routing. Additionally, new data serialization and remote procedure call protocols, BERT and BERT-RPC, were introduced to improve data handling. The changes have resulted in reduced Rails response times and enhanced job queue processing capability, with the architecture designed to provide ample room for future growth and easy scalability.