What is mscorsvw.exe and why is it eating up my CPU? What is this new CLR Optimization Service?

sc.exe stop clr_optimization_v4.0.30319_32
sc.exe config clr_optimization_v4.0.30319_32 start= disabled
sc.exe stop clr_optimization_v4.0.30319_64
sc.exe config clr_optimization_v4.0.30319_64 start= disabled

c:\Windows\Microsoft.NET\Framework\v4.0.30319\ngen.exe display
c:\Windows\Microsoft.NET\Framework64\v4.0.30319\ngen.exe display
ngen.exe executequeueditems