Horizontal scaling of MxRuntimes is already supported which is great.
You can still run into performance problems, because a lot of times the database is the bottleneck.
AWS Aurora is a 100% transparant postgreSQL database cluster so the query load can distributed over the cluster.
We tested it by deploying a docker image to Amazon Elastic Beanstalk and connected a Aurora database (cluster) of 2 postgres databases.
This is working great and for READ intensive database this can be a dramatic performance win. (in a cluster you have 1 write database and N read replica databases)
There is no need to change anything to the MxRuntime since it's 100% transparent and you have only 1 database endpoint. So the feature request is to support Aurora from the cloud portal so large database can stay in the MxCloud v4
Imo this could be the next big step in database performance to create enterprise applications.