Scale to one: How Fluid solves cold starts

Vercel addresses the long-standing issue of cold starts in serverless computing, which occur when a serverless function must initialize from scratch, causing delays for users. Traditional serverless platforms often face a trade-off between cost and performance, as they shut down inactive instances to save money but introduce latency when traffic returns. Vercel's innovative approach, powered by Fluid compute, nearly eliminates cold starts by keeping instances warm and ready to handle requests, ensuring 99.37% of requests experience no cold starts. Their solution involves multiple strategies, including scaling to one, predictive scaling, and bytecode caching, which together reduce the frequency and impact of cold starts. Additionally, Vercel implements rolling releases to prevent deployment-induced cold starts by gradually shifting traffic to new deployments. This comprehensive strategy ensures that applications remain responsive and efficient, regardless of scale, allowing developers to maintain optimal performance without sacrificing cost-efficiency.