Well, you can populate and index a B-tree with the values, then the highest can be found fairly quickly.
Others might not agree. Sometimes you want fast list insertions with something like a doubly-linked list. But you’ll need to iterate the nodes to find the highest.
Also the possibility of copying it all to another array, bubble sorting, then using the first or last array element (depending on whether you sorted in ascending or descending order).
On the back of my napkin here, I’ve come up with yet another approach: look the list over, write the biggest number you find on a Post-It, then stick that to the PanelView.