The loops run the same way as fastloops; that is, instantly.

The following article applies to every loop type, named and unnamed, on Relay and Blue, in Server and Client.

Consider these example events:

Try to predict what the list would look like. And here's the results:

Note that event 1's "after loop" action is not run before Event 2.

You can think of it like event 1 was interrupted; Event 1 does not resume until after the loop has started, looped every channel, and run its finished event, and only then does event 1 resume.

This is the same way Fusion's fastloops work – although foreach loops work differently, and run as if they were the last action in the event.

Due to this "interruption", using lots of events is bad for a project, whether it's Lacewing loops or otherwise; interrupts that take too long will prevent the game's display from updating, making it visibly stutter or freeze entirely.

As an additional note, unlike usual triggered events for Lacewing, loop events don't run for all Lacewing instances including subapps, they only run for the instance that starts the loop. This is covered more under the When selection is changed article.