Percona vs MySQL
Percona Server is a fork of MySQL that came into being about 7 years ago. The Percona employees are mostly former MySQL people. They care about InnoDB performance so much that they inject 30,000 lines of code into its version of MySQL to make those enhancements possible. They have been doing this since MySQL 5.0 and are still at it today.
MySQL (eh Oracle [still hate saying it]) has been trying to keep up with it Percona via its InnoDB plugin (since MySQL 5.1.38, now fully native in MySQL 5.5)
Percona once did an aggressive comparison of MySQL versions. In most cases LEFT UNCONFIGURED, older versions of MySQL outperform newer versions. You must tune MySQL to get the most of it. Switching to Percona may not get enhancements you are looking for. Even with Percona, you must find out what performance enhancements come out-of-the-box and what is settings you need to configure otherwise.
Other posts I hope you find helpful
- Possible to make MySQL use more than one core?
- How do I properly perform a MySQL bake-off?
- Multi cores and MySQL Performance
- About single threaded versus multithreaded databases performance
As well as RolandoMySQLDBA's answer, my observation is that Percona offers features that
- come only with "paid for" stock mySQL
- make it more that a "grown up" RDBMS
Examples:
- Percona XtraDB Cluster acts more like a proper HA solution as per the CAP theorem
- Online backups
- More knobs and levers and monitoring
Assuming like for like performance, the extra kit from Percona makes MySQL far more viable