Performance comparison in ways a SSIS package can be run
Performance should be the same between running it as a job, via DTEXEC or BIDS.

If the package is run on the SQL Server is uses SQL Servers's buffer pool as it queries the data, then SSIS will use it's own memory space to do work.

If the package is run on the client machine it'll use the SQL Server's buffer pool and memory on the client machine.

Running packages on other machines is usually slower, especially if there is a lot of data to move as the data has to be moved over the network.