What’s the Best Programming Language for a High-Performance REST API?

Honestly, focusing too much on performance can be a trap. Almost all programming languages these days can handle REST APIs efficiently. It's more about how effectively you can work with the language. If you pick something you're productive in, you'll get your API out quicker. If performance becomes an issue down the line, then you can consider a rewrite. For now, I think Go is a solid choice, but you should really pick the language that you feel most comfortable with.

For the majority of applications, you'll probably face limits with your file system or network bandwidth before language performance becomes a real concern. So, I'd suggest going with whatever language you already know and are comfortable with. Trying to squeeze out performance from language choice might lead you down a rabbit hole.

When you think about performance, remember that issues usually come from the network or database before they do from the language itself. Most languages from the last few decades should be fast enough for typical use cases. Also, be clear about what you mean by scalability—it's more about your architecture than the choice of language. And about the AI integration, be careful; REST APIs typically expect consistent responses, which is a bit contrary to what AI does. So think about how you want to structure that part.