File size for a world is very important. People often look at the file size for a world as a representation of whether the world will be optimized or not. Though, this isn’t exactly true, the world size does signify how much stuff is in the world. Large file sizes can deter a player from wanting to visit the world, but it can also be a clue that a world is going to have a lot of content in it. I like to achieve the smallest world size possible. I believe having a smaller world size makes the world more accessible to players. Here is how I handle files for my worlds.
I compress almost everything in my world, to an extent. I try to get my world size down to as small as possible, while still having a high level of quality. High detailed textures means large files, so while compressing the textures will get the file size down, it also begins to deteriorate the quality of the file. It’s about finding a nice balance between these two. You want a small file, but you also want quality. Depending on the object and texture, you can decide how much detail you save. If its something the player will see more, you’ll want to keep more detail on that object, but some object in the background doesn’t need to be high res.
FBX files with a lot of polygons can add a lot to file size. More faces means bigger FBX file. A couple million triangles on a FBX file can add something like 30mb to the world size. Worlds can often get this big, but they usually never actually have to be. Modeling as low poly as possible and baking normals, can help reduce the amount of polygons you end up using, which will then give you a smaller file. The only way to compress a 3D model is to have less detail.
This kind of falls under “compress everything” but I figured I’d mention it separately. I tell people to compress textures all the time, but a lot of people forget to compress their lightmaps. Depending on what’s in a world, your lightmaps can be huge. High detailed lightmaps can make a world look amazing, but sometimes I find it necessary to compress them to a lower resolution in order to bring the file size down by a ton.
If you’re having trouble trying to find what is causing your world to be so large, you can look in the profile overview in unity to see what is taking up your space. For something as specific ass VRChat you can use community tools like the VRChat Toolkit developed by a user named one. This toolkit allows you to see all your files in the world, organized from largest to smallest.