I'd go with MySQL. There are better tools, it is less expensive and easier to scale. I don't have any straight-up "speed" evidence other than what is anecdota

I'd go with MySQL. There are better tools, it is less expensive and easier to scale. I don't have any straight-up "speed" evidence other than what is anecdotal. If you're worried about the MySQL license, you should try PostgreSQL. I've been using it for three years and have had nothing but extremely positive results. Version 8.3 is stupidly fast.