Optimize image score dropped significantly

Hi guys,
I seems to be struggeling with speeding up my page performance when it comes to images.
When I first signed up for Hummingbird and WP Smush Pro my image score was around the 40s.

To improve my image performance I then started to delete the biggest images, shrink them and uploaded them again. I then did a resmush. But nevertheless my score now dropped to a 4!!!

What am I doing wrong?
Could it be the slider on my page?

Thanks for your help guys.
Cheers,
Stef