Cursor hover on the Performance graph is not steady when moving the cursor out of graph.

Steps to reproduce:
1. Open the Performance page.
2. Let the graph running for a while and pause.
3. Hover the cursor over the previous timeline in a graph.
4. It is unable to place the cursor to the previous timeline and then move the cursor out of the graph in order to scroll the hottest collections box or slowest operations box. Moving the cursor out of the graph, it will be placed at the latest time.