MySQL Amazon Aurora - a few slow queries causing extreme performance issues

I'm a dev, not a DBA, so pardon my ignorance. I'm running on MySQL Amazon Aurora, single-instance (with a replica for failover). A few days ago, my application had a handful of *extremely* slow queries (15min+) run simultaneously. I'm planning on optimizing those queries, but looking at the Aurora metrics for the waits, I'm curious about a couple of things. The spike from 18:30-19:00 is when the db was barely keeping up, slowing down the entire application. - Is it normal for a handful of long-running queries to cause an extreme bottleneck across the db? - Is there some way to terminate long-running queries after N number of seconds? - Does the wait/io/table/sql/handler indicate that the db was busy running queries?