When you have more than one rule set to fire on a control, view, or form, the order in which the rules are set to execute can impact the performance of that Form:

--then complete the following one after another

--then start the following asynchronously

--then complete the following in a batch

--then complete the following concurrently

Knowing which option to choose can be challenging if you do not understand the impact of each. The following video by K2 describes each of these options in a bit more detail, as well as providing some basic metrics derived from each:

Using execution types to improve SmartForms performance