Sometimes CIL Compilation take a lot of time and sometime freeze.
Often this occur because there are some batch running or some users that are running some process that use CIL Objects, etc.
In these situation, the DLL are locked and so CIL go in hang.
The best practices about CIL Compilation, is execute in a non-peak hour because during CIL Compilation AIF Services are stopped, so :
1- SSRS Report doesn’t work
2- Office Add-in doesn’t work
3- Eventually Custom Services ( Integration with WMS, integration with some Web sites, etc. ) doesn’t work