No there has been no load testing done. It is also quite hard as it would depend a lot on the hardware and even more on what exactly the workflow is doing. If you would like to do a lot of short running workflows I would advise to set EXECUTIONS_PROCESS=main
Because if that option gets set, it executes everything in the main process. If that does not get set, it creates (by default) a new process for every workflow execution and this has obviously much more overhead and the startup time increases a lot. From a few ms to like almost a second.
Here a related topic which talks about it: