If you are looking for an optimized file, then file size is not the right direction. Even a 100 MB file can be awfully slow while a 3 GB project goes very well on the same computer.
Instead, I suggest to keep your attributes clean, do not use too many Solid Element Operations (SEOs), limit the number of polygons, etc.
When a project is well structured and organized, and even the computer under it matches the needed resources, it should be right.
Customer Engagement Expert, Community Admin