If I'm reading this correctly this only applies to the .NET 4 runtime and not the old .NET 2.0 runtime (also powering .NET 3.0 and 3.5 solutions).

In that case I guess if you are running tail-recursion heavy algorithms on x64, just recompiling the same old code for the .NET 4 runtime should yield runtime improvements.

Would be interesting if someone had any actual measurements for this.