Sometimes, the size of a PPT file with less than 20 pages will exceed 50M, and it is easy to get stuck when playing in full screen. So how to compress PPT files?
1. Compress pictures. Double-click the picture, choose to compress the picture, and then operate as shown below.
2. Select File-Advanced-Image Size and Quality, and set as shown below, then save. 
Basically, according to the above operation, the PPT file can be reduced a lot.