I have faced the same problem with version 6.10.3, because I used to have a module with many module roles. It used to take a lot of time when checking for error when the 'Check security' was enabled. I have submited a support ticket on that and Mendix Support Team advised to enable this feature at the end of development before comitting changes. I guess when having lots of module roles the time in checking for errors increases when the 'Check security' feature is enabled. I suggest to disable this feature and turnin it on before committing your changes as Mendix advised. :)