Functional Programming Is a Bad Thing for Performance

I think at least in like app development, we've definitely gravitated more towards the functional style. It's just kind of easier to read than a for loop with a bunch of stuff happening inside it. There's also like subtle performance implications to this as well,.functional programming often looks like it might be way worse for performance than just doing things like in a mutable array in a for loop. So again, having an understanding of what's going on under the hood is often important.