Techniques for determining differences between document object models (DOMs) received in response to asynchronous functionality calls is described herein. The techniques may include clustering elements in a webpage having asynchronous functionality. The techniques include executing asynchronous functionality calls for two of the elements that form a cluster, and receiving a document object model (DOM) in response to each of the asynchronous functionality calls. The DOMs are compared to determine whether a difference exists between the DOMs based on a predetermined threshold. If no difference exists, execution of the asynchronous functionality calls is ceased.