This doesn’t make sense to me. How can Aurora give you 5x better performance than MySQL or 3x better performance than PostgreSQL.. "while delivering similar performance"?
I suspect this is an example of a badly worded sentence. The wording you list can be found on the Amazon introduction for Aurora, see https://aws.amazon.com/about-aws/whats-new/2014/11/12/introducing-amazon-rds-for-aurora/:
Amazon Aurora provides up to five times better performance than MySQL at a price point one tenth that of a commercial database while delivering similar performance and availability.
This wording is no longer used and is replaced on the current product page at https://aws.amazon.com/rds/aurora/ :
Amazon Aurora is up to five times faster than standard MySQL databases and three times faster than standard PostgreSQL databases. It provides the security, availability, and reliability of commercial databases at 1/10th the cost.