I always read on the web "Use concatenation & minification for a faster site".
But I'm wondering, Is it necessary to concatenate my scripts if I am using AMD library like requireJs or SystemJs to load the scripts asynchronously?
IMO, it is especially important for applications with AMD libraries. One of the key reasons for optimization is to reduce the number of HTTP requests made to the server. Also, the front-end will be faster without network latency in the picture. Using AMD makes writing client side code seem more organized and promotes SOC, both can result in having a ton of files needed for a single feature.