We've switched our static pages from nginx to HAProxy. Using stick tables, traffic rules and ACLs allowed us to have better control over our traffic while load balancing. Also, performance gain with latency, threads, and processes.
We’ve recently migrated our core service from Node.js to Golang. Despite recent major updates for #Node.js v10.x with ES6 and async/await, performance gain with golang still remains enormous. Also in terms of concurrency and scalability, golang excels.