Underdog,

Have these packages been deployed to a production or are you just running them locally? Just a hunch but that may be why you're seeing such shotty performance...

Also, you said that your T-SQL scripts run from a staging area. This implies there is already some ETL processing that occurs before your T-SQL scripts are executed. Do you have direct access to the source files? If so you may look at taking the source data and performing all the transforms in memory (new feature SSIS brings to the table) which could add some value towards your performance goals overall...