I'm making a 3D game, and I want to create a 500 by 500 map. However, anything above 50x50, and Unity starts to freeze and slow down. The compiling time for the Tilemap is also quite long. My PC specs  is fairly good, so am I doing something wrong? I bought it on the Unity store and can show you the invoice if needed.

i also wanted to ask if it's possible to use   more than 1  Gameobject when generating terrain in 3d.

ty , for you answer, i managed to figure out the multiple layers thing.