CiviCRM on MariaDB instead of mySQL
We have mariadb on our newest server, it's a completely transparent replacement. I haven't noticed any major speed change, either better or worse, so I'd take your hope of major speed gain with a pinch of salt. 

We switched to it mostly because they seem to do a better job at pushing new features than oracle... and because it looks like 100% the same, as viewed from civi