Duane Douglas (also of the great twitter aggregator http://twitter.com/SSISBI) had made two greatblog posts about “Optimizing SSIS Package Performance”:
Needless to say, SSIS packages should run as fast as possible. However, accomplishing this is easier said than done. Performance tuning SSIS packages isn’t for the faint of heart — it involves a lot of work and and a low-level understanding of what happens under-the-hood when a package is executing.
Very much worth the read:
Optimizing SSIS Package Performance – Part 1
Optimizing SSIS Package Performance – Part 2: The Data Flow Components
And while you’re at it the Top 10 SQL Server Integration Services Best Practices could gain you another great insight under the hood of SSIS.