Default File Size Shrink

I recently realized how much a default file size for blender is very strange for me. I downloaded a file called easyemit (if you’ve heard of it) and the file size is 277 KB. It has tons of code and objects in it. I save the default start scene (just a cube, lamp and camera) and it is 420KB…why is this? how do I shrink it down?

When you save your blend file do you enable the ‘Compress’ option in the blender file browser

Ahh…so I don’t. This helps a lot. Thanks
but does this decrease any performance or anything?
Is there a way to automatically compress?