I make use of Lua and Redis for handling a few million redirects and have been happy with it so far. I never considered MySQL due to performance concerns. 3ms

I make use of Lua and Redis for handling a few million redirects and have been happy with it so far. I never considered MySQL due to performance concerns. 3ms for connection setup + auth + query seems reasonable. Are you using persistent DB connections? Any other mods? What sort of timeouts have you configured for DB connections?