Agree that the whiteboard thing is often not applicable but it's so nice when a developer has efficient code if only because it indicates that they know what's going on and also that there are fewer bugs and other bottlenecks in the system.

Those bugs don’t come from using the wrong algorithm, they come from not understanding the business case of what you’re writing. Most performance issues in the real world for most cases don’t have anything to do with the code. It’s networking, databases, etc.

Your login isn’t slow because the developer couldn’t do leetcode