There is news on the faster F# Printf.* story. We released an alternative implementation as a package today. NuGet: IntelliFactory.Printf Source: https://bitbucket.org/IntelliFactory/printf Some background: F# Printf.* functions are a very nice interface for formatted printing, but the default implementation is quite slow, which is undesirable for production use (say, for logging inside a server). I believe the F# team is addressing this for their next release - and when it comes, it is going to be aw[...]