Have you tried first-person mode? The way the characters' skin looks up close? The clothes textures when you cluse up on them? Improving the quality of those textures without compromising the game's performance is a matter of optimization.
Instances. There are characters that appear at certain times in certain places (park, pool). It was mentioned in this thread a while ago, that all character instances are in all the places they should be, just "invisible." The game determines whether to make them visible or not. Having them invisible is a silly system overload.
Techniques such as asynchronous scene loading, lazy prefab instantiation, or the use of AssetBundles can be used. These techniques allow resources to be loaded only when needed, improving performance and reducing initial load times.
