The problem is that it dates your posts, so your click-through & time on page could be negatively impacted if the audience believes it's outdated information.

My advice is to make the change and check the performance speed after. I believe that Wordpress has addressed this issue anyway with this update. If you are worried you can add a post ID to the post name tag, but I personally wouldn't be worried about it. If performance is truly that bad you can always go back.