If you see the following warning message in the browser console, this occurs if your component sets the items attribute of an <aura:iteration> tag multiple times in the same rendering cycle:
"WARNING: [Performance degradation] markup://aura:iteration [id:5:0] in c:iterationMultipleItemsSet ["3:0"] had multiple items set in the same Aura cycle"
The following code shows how <indexentry content="events strategy: tag"> you can generate performance degradation when using aura:iteration.
<!--c:iterationMultipleItemsSet--><aura:component> <aura:attribute name="sports" type="List" default="[ 'Cricket', 'Tennis', 'Football' ]"/> <aura:handler name="init" value="{!this}" action="{!c.init}"/> <aura:iteration ...