PageSpeed Insights is a google powered tool located at https://developers.google.com/speed/pagespeed/insights/ . It gives suggestions on how to speed up your site.
If you’re an adwords user, you may encounter the suggestion to compress images located at https://tpc.googlesyndication.com/icore_images/ Unfortunately, you will not be able to compress these images, as they are located on google’s servers as part of their ad infrastructure.
I’ve submitted a bug report to google via their complaint form requesting they optimize their ad infrastructure images. I encourage anyone coming to this page to submit a complaint at https://support.google.com/adwords/contact/aw_complaint.
PLEASE SUBMIT A COMPLAINT TOO!!