Do I re upload them in the cache directory?

Could you confirm the path according to what has been crawled in the Google PageSpeed Insights reference I pasted in my first post?

You can use the following Joomla! extension for automated image optimization:

www.imagerecycle.com/

Do you recommend it Joe?

I have yet to use it as a plugin - I used the web app version - I even wrote an article about it:

www.cloudaccess.net/fresh/blog/entry/2017/03/24/top-3-online-image-optimizers.html

Kudos buddy :)

i see something i picture compress

after convert image with K2 image resolution change to 96

for normal image ( in monitor tv or any digital device ) must or better be 72
more than 72 = no different because monitors not support it

and this change need more size for example

with photoshop
image 600 * 900 with resolution 96 = 150k
image 600 * 900 with resolution 72 = 100k
compress for web 96 = 53k
compress for web 72 = 36k

now this is be nice if in K2 you change something after conver image resolution change to 72 or add some code like other pluging for optimize images then save