Connection pooling
Applies to: 
.NET Framework
.NET
.NET Standard
Connecting to a data source can be time consuming. To minimize the cost of opening connections, ADO.NET uses an optimization technique called connection pooling, which minimizes the cost of repeatedly opening and closing connections.
In this section
SQL Server Connection Pooling (ADO.NET)
Provides an overview of connection pooling and describes how connection pooling works in SQL Server.