1, the improved method is to double-click the file first, and the file loading speed is slow.

2.i opened it. There are not so many things in it.

3. This is because in the process of drawing, various blocks, layers and styles are established. With the revision of the drawings, many of them are useless and hidden in the archives.

4. Enter the shortcut key PU at the command line.

5. Click Clean All to open a dialog box to confirm cleaning. Click Yes to All. After cleaning, ctrl+s saves the file.