In the old Cloud Flow Designer, there was a specific element that existed for Fast Updating records.
In the new Flow Builder, it still exists, but it was just merged along with the Update Records element which lets you choose whether you’d like to update a specific object/record with certain criteria or if you’d just like to update a collection variable in your flow (aka a fast update).
My latest video not only shows how to utilize a fast update, but also shows how you know longer need process builder to initiate the flow. By using the new record-changed flow feature, flows have become autonomous.
A fast update can be considered best practice when you are updating a large group of records, as it should require less SOQL queries which could lead to hitting governor limits. One thing to note is that although fast updates are best practice for updating a small or large set of records, you can still run into complications if triggers are active / packages are installed with triggers on the object(s) that you’re updating. I plan on making a video about this scenario soon as I’ve dealt with it and can sometimes leave you screwed in terms of having your flow be successful.