The graphics show the biggest free features of patch 1.7. I've heard from people online that the performance improvements are quite real.

Here is the changelog https://forum.paradoxplaza.com/forum/developer-diary/victoria-3-dev-diary-122-sphere-of-influence-and-update-1-7-kahwah-changelog.1689255/

Im currently busy with a Stellaris game but I will check out Vicky 3 again after some hotfixes.