Sometimes, you may want to slow a data feed for testing purposes. In these cases, you can throttle your source–slow it to a specified number of rows per second. but you can adjust this default rate in project settings. You can also set throttling by pipeline guide using the Throttle command.
To throttle a source:
You can use the Throttle All and Unthrottle All buttons on the Sources page to change throttling for all sources at once.
To change throttling for individual sources once you have added them, click the rocket icon in the upper right hand corner of the source: