https://support.microsoft.com/en-gb/topic/kb3097636-fix-performance-decrease-when-application-with-connection-pooling-frequently-connects-or-disconnects-in-sql-server-d06a8d38-d6dc-0f86-fa94-8a7af1ea1796
KB3097636 - FIX: Performance decrease when application with connection pooling frequently connects...
Fixes an issue in which you may experience a severe performance decrease when many same logins connect to a database in SQL Server 2012 or SQL Server 2014.
connection poolingfixperformancedecrease