WP Smush.it - still getting low score for Google PageSpeed Insights

Hi support team,

I recently did a bulk super smush of all of the images on this site - which was running slow due to the need to optimise images. The site got a 63/100 on Google PageSpeed Insights before the super smush and then it got the same score again today... Despite the images being compressed by 20%. Do I need to clear a cache somewhere to get an updated score or does it take some time for the results to be updated with Google (ie via a robot crawl etc?)...