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?
Currently IronRuby is pretty slow in most regards.  It's definitely slower than MRI (Matz' Ruby Implementation) overall, though in some places they're faster.
IronRuby does have the potential to be much faster, though I doubt they'll ever get near C# in terms of speed.  In most cases it just doesn't matter.  A database call will probably make up 90% of the overall duration of a web request, for example.
I suspect the team will go for language-completeness rather than performance first.  This will allow you to run IronRuby & run most ruby programs when 1.0 ships, then they can improve perf as they go.
I suspect IronPython has a similar story.
Dynamic .NET language performance?