[Q] Optimized Terrain

Hello Everyone! I apologize if this post isn't as organized as it should be.

Every now and then I try my hand at making a 3D terrain system for my game. It's typically a gdscript that reads coordinates in a json, dict, array, etc and then instances each point as a terrain node/tile (so I can dynamically change each tile). The primary issue I run into is lag with reading this data over and over causing lag and the many instances of nodes themselves potentially causing lag.

I have successfully implemented a render distance before, which I believe fixed the instance count (IRC works good for max 5k objects). The issue that I believe stopped me was the lag from looping over an extremely long dictionary every second (or less). The looping was so when the player moved, it rendered a new group of tiles based on the player location.

It took a long time to ask someone else for help with this because I didn't keep track of my small terrain test projects. I do not have any examples of what I've done before at the moment, so take this as someone asking for help on finding and setting up an easily managable 3D terrain system for Godot 3.5.x.