Thanks for the help! The performance score did rise after I follow your instructions.
However, there are still some pictures that are recommended to be compressed in the list.
The first three, as you said, are from the third party site. Should I just ignore them?
And for the last three, I tried Directory Smush to compress them, but they still show up on the improvement list. I was just wondering if it still matters because the load time of my website has already improved so much.
Thanks again for your help!