Many aspects of XRP, from server hosting, load-balancing, content management/delivery, etc, take advantage of the awesome power of AWS (Amazon Web Services). In terms of performace at scale, the best version of XRPlatform relies on more than a dozen services in the AWS ecosystem.
While XRP's code and databases can run entirely on one server, by decoupling these into dedicated services (EC2 for the application code, RDS and Elasticache for databases, ALB for load balancing), XRP is equally performant when dealing with thousands of simultaneous users or just a handful.
XRP's database engine is PostgreSQL, which is hosted and managed via RDS. XRP owes much of its usability to the SQLAlchemy ORM which makes complex queries simple for users to interact with and for developers to iterate on. Redis, via Elasticache, handles data which isn't SQL-friendly.
XRP uses Route53 for its DNS hosting & management, which enables simple routing to load balancers and Cloudfront (CDN) distrobutions unlike other DNS management services. Speaking of Cloudfront, XRP uses it for caching, image-handling, robust content delivery worldwide, and a small but growing number of serverless offerings.