Miki I'm going to say this with a lot of love right now. It's great you are making a game, but you are probably being taught by geezers that think this kind of stuff matters. It just doesn't. Not since before you born.
As a practice in efficiency then yeah, it might matter academically. But if you want to make an RL then system performance is a moot point.
I'm not trying to be a jackwagon by pointing this out, there are going to be a TON of people here with way better programming skills than I have, but most hobby type roguelikes are rolling in at less (far less) than 10 megabytes.
Old dudes who grew up trying to save bits and bytes as a primary skill in programming might not be aware that efficiency is no longer a major skill. And when it comes to tile based, turn based and ascii graphics games efficiency considerations are not an issue.
Nethack and ADOM and Diablo are all much more complex than you will create on your own in the next decade, and they all run fine.
I mean this to be taken as encouragement and i'm sorry if this seems negative.
Make a game. I'll play it.