I have been running a bunch of generated static pages via GH (and now GitLab) and never seen any disadvantage, but don't take me wrong - I am always learning :)
Deploy a Blog site with Gitlab pages and Cloudflare
Netlify was just a lot quicker to get started. It automatically compresses images, js, etc., if you tell it to. It automatically deploys branches to a special subdomain, so you can share previews of branches with other people. Also, though I haven't used that yet, it has this "Functions" thing that would allow you to add dynamic behaviour to your static website.
 - https://docs.gitlab.com/ee/user/project/pages/
 - https://about.gitlab.com/direction/release/pages/