Google PageSpeed accused the images of my articles were great.



I decrease the size of the image files and I changed them all in the picture and the Google tool accuses the same size as before.



What can be happening? k2 have image cache?

I got the same issue (And others regarding quality of images), trying to optimize the speed of my site.

Yes, K2 makes its own imagecache.

The problem with this, as far as I know, is that no matter what image size you upload to your site, K2 will create its own thumbnails and images (in different resolutions), on every new article/item.

I've tried to solve this with different plugins (Eg. JCH OPTIMIZER PRO), but it didnt work for my site. I've got several new articles with images every day on my frontpage, so I would have to do the trick many times a day.

I thnik if you've got a static site, without daily/weekly updates, JCH OPTIMIZER PRO might wotk for you.

Many others have the same problem, but I havent found a solution yet, and cant Google the solution.

Sincerely,
Martin

PHP Image compressing can be a bit sub-par compared to other tools.
Unfortunately the other tools cannot be ran server-side.
There are several apps like pngcrush, imageoptim which can be ran client-side.