How does PageSpeed ​​Insights determine if files are compressed?

Question

Image processing

Hello.
Google swears that some of the images on my site can be compressed. Almost by 50%. At the same time, I already perverted with them as best I could.
1) Removed all meta-data using jStrip
2) Passed the files through FileOptimizer
3) Passed the files through https://tinyjpg.com/
And anyway, Google tells me that I can compress this whole thing by 64%
What should I use to finally satisfy Google?

Answer 1

do not scale images, that is, adjust the size of the image to the size on the screen.

Answer 2

Turn off your inner perfectionist and take this PageSpeed ​​Test. You already have a great site as long as it loads no longer than 3 seconds.