The template shows very large images where they should be thumbnails.
any way to change this?
Larger image = more loading time.
I estimate that the right size for this would be 300x200.
This happens to me using:
"grid with sidebar".
That's intended, we added bigger image to support retina display without problems, also there is an option to use the grid with 2 columns so the size must be bigger enough.
I highly recommend you to use the optimized image field http://prntscr.com/mjoick so you can upload images of any size you want (for example 300x200) also it is super recommended to compress that image with Toolur: http://estudiopatagon.com/themes/docs/reco-wp/#o-2 so you will get the best possible load time (that's why we added that field), Wordpress scale and compression are not the best, so you can get better results with Toolur.
Important: you can apply this solution only for your last 9 posts, Google first of anything, will check your homepage speed to assign you a score.
Hope this information may help you!