I think Node.js is unsuitable for normal routing tasks like this because of single-threaded runtime. This could be achieved really easily with popular web serve

I think Node.js is unsuitable for normal routing tasks like this because of single-threaded runtime. This could be achieved really easily with popular web servers like nginx or caddy. If I remember correctly, there was a lot of tutorial about serving static files using nginx in front of express.js/koa.js for better performance and that serving static files doesn't compete with the dynamic part of the website.