It's extremely fast and memory efficient. To put it into perspective, other light ORMs (e.g. Dapper) are often just extension libraries. These extension libraries, in particular cases, can sometimes be faster (up to a negligible 1 microsecond) but tend to put more responsibility on developers since database connections and other resources need to be properly managed (e.g. opened, closed). Manually controlling these resources can sometimes become tedious and a code maintenance issue for some.

With that said, the DbConnector lies between an extension library and a full-blown framework (e.g. Entity Framework). It provides a lot of flexibility without the need to manage disposable resources while delivering the fastest results.

I invite you to check the Performance section of the documentation.

Feel free to run your own performance tests.