LocalDB 2014 vs 2008 UserInstance shutdown/stop performance degradation

Hi,
We have recently upgraded from SQL Server Express 2008 R2 to SQL Server Express LocalDB 2014. The performance is roughly similar in most cases (certain operations are faster on higher spec machines), except for stopping the user instance either through talking to SQLLocalDB.exe utility directly or through executing the "shutdown" command on the SqlConnection.
In other words when executing from command line:
> SQLLocalDB.exe create Test // 3-4 seconds
> SQLLocalDB.exe start Test // 2-3 seconds
> SQLLocalDB.exe stop Test // 6-8 seconds
> SQLLocalDB.exe delete Test // ~1 second
As far as I understand calling SQLLocalDB.exe stop Name is the same as executing the "shutdown" command on the existing SqlConnection. The timing is certainly similar.
What I don't understand is why executing the "shutdown" command on 2008 R2 database was almost instant, but executing ...