this terrible lag comes from an Mutter / Gala / NVIDIA / XServer regression currently on Ubuntu, that i couldn’t fix! really sorry about that!
also apart Blur and Shortcuts Help, everything else are already on Juno!
▶ my post with a short guide how to test latest elementary desktop on Ubuntu 18.04, at least till they release official images
▶ the blur API for Gala, is experimental, and it may…