I understand that IronPython is an implementation of Python on the .NET platform just like IronRuby is an implementation of Ruby and F# is more or less OCaml.  
What I can't seem to grasp is whether these languages perform closer to their "ancestors" or closer to something like C# in terms of speed.  For example, is IronPython somehow "compiled" down to the same bytecode used by C# and, therefore, will run just as fast?
IronPython and IronRuby are built on top of the DLR -- dynamic language runtime -- and are compiled to CIL (the bytecode used by .NET) on the fly.  They're slower than C# but faaaaaaar faster than their non-.NET counterparts.  There aren't any decent benchmarks out there, to my knowledge, but you'll see the difference.
Dynamic .NET language performance?