SqlPerf blog on SSIS performance
Runying Mao and Len Wyatt did a great study of SSIS performance, and posted some results:
Getting Optimal Performance with Integration Services Lookups
OLEDB Source with Views
BLOB and buffer temporary storage
SSIS Performance Counters
https://blogs.msdn.com/sqlperf/archive/2007/05/01/something-about-ssis-performance-counters.aspx
Buffer size adjustments
https://blogs.msdn.com/sqlperf/archive/2007/05/11/adjust-buffer-size-in-ssis-data-flow-task.aspx
Parallel execution
https://blogs.msdn.com/sqlperf/archive/2007/05/11/implement-parallel-execution-in-ssis.aspx