What is the best way to manage data for a large tile map?

My plan was to activate or deactivate areas of the map based on player position, but the more I think about it I’m not sure activating and deactivating is the best way if I want to keep load times down. What is a good alternative to this?

Preferably I’m not instantiating anything btw, I know that’s an option but I would rather have the tilemap(s) all laid out in the right spots.

How large?

Large, 2 hours worth to traverse.

It doesn’t bog down my system because it’s all 2D and I’ve got a nice gaming PC, but considering this is a pretty lightweight game I want it to be playable on all the various devices.