Does Using -const- Affect Program Performance?

No, it doesn't.

Unlike lower-level languages like C#, where using const can lead to memory optimization and better memory management, in JavaScript, using const doesn't have any impact in this regard. Even considering its use as a form of micro-optimization wouldn't be accurate because it truly doesn't influence performance.

But why should we use const then?

Simply put, it helps us encounter fewer errors when writing code and can lead to more readable code in some cases. It guides us in being mindful about what should not be changed, thus preventing potential bugs from arising in our program.