This test injects 5 divs, div.n1-5, each containing one div.m. Then 1050 new divs are injected into div.n1 div.m, with two classes start and box0-1049, A click event is added and triggered, which then replaces class start with done. Finally the processing time in milliseconds is injected into a new div in the end of the list.
Querying Nodes, manipulating classes, injecting HTML and adding events are probably the most reoccuring actions, handled by a library. These actions will have a considerable impact on how a library performs.