Why Does PC Suddenly Become Normal When I Open Task Manager?

My PC sometimes becomes slow, freezes, or behaves strangely, but the moment I open Task Manager, everything suddenly returns to normal as if the problem disappears. I have noticed this happens randomly, and I am not sure whether Task Manager is changing system behavior, stopping a hidden process, or simply making a background issue disappear temporarily. I would like to know why this happens and how I can identify the real cause without needing to open Task Manager every time.