Yes, optimization is a really important step. I think most big-name games have a selection of different quality levels that you can use to get the best performance.

Creating a user menu with different screen sizes, texture size, detail level for models, whether to use shaders, shadows etc... is an important step in any serious game production.

Also, some of the built in functions like "camera.clip_far" and LOD (Levels of Detail) are critical things for getting any game to run smoothly. I think 3DGS is actually a very powerful engine, but it does not do these things for you automatically.

Also, the way you write your code can have an impact on your game too. I am not an expert in this area, I basically taught myself lite-c by trial and error, but I'm sure some of the more advanced programmers on the forum could explain further.