A method includes providing a graphical user interface (GUI) that allows a user to dynamically change virtual user (VU) distributions of a load test performed on a target website or web application during test run-time. The GUI allowing the user to make a change to a current ramp profile of one or more VU distributions responsive to application of first user input. The first input including dragging an icon to a position in a first graph, the position denoting a future number of VUs at a future time. Following application of the first input, the change to the current ramp profile is visually displayed on a second graph in real-time as the load test progresses.