Polygon Count,
Polygon Count can affect the production of 3D models. The higher the polygon count, the more strain of the processor of your PC. If this strain becomes too much it could lead to the 3D model becoming impossible to edit with ease. To solve this you need to create the models with optimized amount of polygon count to avoid problems.
File Size,
If you don't make sure the file size is fine then you could end up having problems with the 3D model/environments. If your file size is too much it can affect the rendering times which could be problematic. Another thing that can be hindered is the speed of the PC being used because of the amount of data which is being used by the one file.
Rendering Times can be a problem when you are working on 3D models/environments. If these are not optimized in file size etc... can make the rendering time increase. Depending on the size of the scene could take hours, days to be fully rendered.
