Because CAD files actually include two parts of information, one is what you can see on the map, and the other is what you can't see on the map. Invisible information is mainly some internal blocks and unused layers, label styles, text styles, etc. For example, a CAD file is like a stage, and the map you see is like an actor performing on the stage, without unused blocks, layers and labeling styles. The writing style is like an actor waiting for the stage backstage. You only copy and paste the pictures you see. If only one stage performer is invited and the backstage performers are not invited, then the stage, that is, the CAD file, will definitely be reduced. If you clean the original file with PU command before copying and pasting, and then copy and paste, the file will not become smaller. Of course, if you scale the size of the graph, the file size will change slightly, but the change is relatively small. The size difference after copying and pasting should be due to these two main faces. This question you asked is really strange. Although it's not suitable for me, I still can't help but say, why do you make the file bigger when you have nothing to do? If your hard disk is too big, just make the file as big as possible, just like the original one, that is, you build a big block in this picture, delete it in the picture, leave it in the background to occupy space, and then build another one until it is big enough. Is this a good way for me?