David Notario's WebLog What is mscorsvw.exe and why is it eating up my CPU? What is this new CLR Optimization Service? Short version: mscorsvw.exe is precompiling .NET assemblies in the background. Once it's done, it will go away. Typically, after you install the .NET Redist, it will be done with the high priority assemblies in 5 to 10 minutes and then will wait until in Public bookmarkswith cputask