It’s easy for new developers to get caught up spending time on things that really don’t matter. Spending time trying to work out whether approach A is using more or less memory than approach B is a common distraction, and usually the answer to whether it does or not is irrelevant (why would you be concerned if memory for a variable is stored on the heap or the stack, and try to do do ‘weird things’ to reduce memory usage).
It’s important to know if you have a problem or not, and then spend time investigating and resolving that specific problem. Don’t spend time worrying about things that are not important or irrelevant. Knowing what is important often comes with experience, but if you’re unsure then ask one of your more experienced collegues.
[Top tip series: rather than spending time writing lengthy articles over several days I’m going to try and post shorter, hopefully useful tips more frequently]