How the informatica server increases the session performance through partitioning the source?

For a relational sources informatica server creates multiple connections for each parttion of a single source and extracts seperate range of data for each connection.Informatica server reads multiple partitions of a single source concurently.Similarly for loading also informatica server creates multiple connections to the target and loads partitions of data concurently.

For XML and file sources,informatica server reads multiple files concurently.For loading the data informatica server creates a seperate file for each partition(of a source file).U can choose to merge the targets.