Hi kingofpain,
As JR said, we use mysqli instead of mysql, recently, there were a message on PHP's maillist to move from mysql to mysqli (newer, better). This isn't new, from some time ago, but a bit long to tell it here.
We have some good practices (we close manually the connection), but for 2.3 release we want to work on optimization and almost rewrite from scratch the database connection models.
30 users limit is a low limit (usually on shared hosting) it could handle around 50-80 users at the same time, which is a serious amount.