Does showing "featured images" as homepage post thumbnails affect performance?

My blog shows full length posts on the home page. Each one has either an image or a youtube video in it, along with several paragraphs of text. I am considering changing to showing excerpts/teasers, along with the featured image as a thumbnail.

My question is: what is the performance impact of showing thumbnails? The purpose of making this change is to make my page lighter for better performance, but if showing 10-20 thumbnails on the home page is worse, I won’t pursue it.

I am running W3 Total Cache.

It’s a very highly impacted dedicated server already, so every little thing matters.