Synapse and ADF Copy Activity Internals 

In Azure Data Factory (ADF), the maximum number of concurrent connections for a copy activity depends on the type of source and sink data stores you are using. The maximum number of concurrent connections is determined by the data store's capabilities and limitations. For example, if you are copying data from an on-premises SQL Server database to an Azure SQL Database, the maximum number of concurrent connections is determined by the SQL Server's maximum number of concurrent connections and the Azure SQL Database's maximum number of concurrent connections.

In Azure Synapse Analytics, the maximum number of concurrent connections for a copy activity is determined by the number of concurrent queries you have configured for your service. By default, the maximum number of concurrent queries is set to 32

 

 Performance : 

1. Increase you max number of concurrent connections